Management of gastro-intestinal disorders

ABSTRACT

The present invention relates to the field of methods and apparatus for the determination of various conditions of gastric and gastro-intestinal malfunction, especially those performed by means of breath tests.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.10/519,723, which was filed on Jul. 26, 2005 (now U.S. Pat. No.7,338,444), which is the national phase of PCT applicationPCT/IL03/00178 filed Mar. 6, 2003 which claims the benefit of U.S.Application No. 60/392,514 filed Jun. 28, 2002 and PCT ApplicationPCT/IL02/00702 filed Aug. 22, 2002. The disclosures of all theseapplications, are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of methods and apparatus forthe determination of various conditions of gastric and gastro-intestinalmalfunction, especially those performed by means of breath tests.

BACKGROUND OF THE INVENTION

It is estimated that more than 25% of the general population indeveloped countries suffer from different degrees of functionaldyspepsia and/or Irritable Bowel Syndrome, IBS. Such conditions arecalled for the purposes of this application, functional GI disorders.These disorders are clinical syndromes characterized by GI symptomswithout identifiable cause. When a physiological cause is identified,these disorders are more correctly called organic dyspepsia or boweldisorders. The complex of dyspeptic symptoms is usually related to painor discomfort generally felt in the center of the abdomen around orabove the navel. Some examples of discomfort include fullness, earlysatiety, which is a feeling of fullness soon after starting to eat,bloating and nausea. There is no single organic disorder that explainsall these symptoms, although about a third of all patients with thesesymptoms have delayed gastric emptying, though not usually so severethat it causes frequent vomiting. Additionally, a third also show afailure of the relaxation of the upper stomach following an ingestion offood, a condition known as abnormal gastric accommodation reflex. Theprevalence of delayed gastric emptying in these patients is notsignificantly higher compared to asymptomatic individuals, but abouthalf of the patients with these symptoms also have a sensitive orirritable stomach which causes sensations of discomfort when the stomachcontains even small volumes. A gastric emptying study can show whetherthere is poor emptying of the stomach. Other motility disorders are moredifficult to detect, but recently, there has been developed, asdescribed for instance in “Practical Guide to Gastrointestinal FunctionTesting”, by C. Stendal, pages 194-201, published by Blackwell ScienceLtd, Oxford, U.K., (1997), methods using an intragastric balloonconnected to a computer-controlled pump called a barostat, which canshow:

-   (a) distention or whether the upper stomach relaxes adequately    during eating, and-   (b) how much filling of the stomach it takes to cause pain or    discomfort or gastric accommodation.

Barostat studies have shown the relation between dyspepsia symptoms andimpaired accommodation by means of measuring stomach volumes as afunction of intra-gastric pressure, or vice versa, and/or thesymptomatic response to changes in intragastric pressure at differentgastric volumes. In such barostat procedures, a liquid meal isadministered, which can be either a high volume of water (up to 2liters), an isotonic or high caloric value solution such as Ensure orGatorade, a soup or a glucagon infusion. Then, for a given volume of theballoon, the pressure needed to induce gastric discomfort or pain ismeasured. This method is invasive, uncomfortable to the patient andimpractical for wide clinical use. Furthermore, the barostat bag mayinterfere with gastric motility resulting in an inaccurate result.Another example of an organic cause of dyspepsia is a Helicobacterpylori infection.

Asymptomatic patients in risk groups such as diabetic patients, patientsunder drug therapy for Parkinson's Disease, and others, also benefitfrom investigations for determining specific GI disorders, which canaffect the prognosis of their main diseases. For example, disturbedgastric emptying may affect the glycemic control in diabetic patients.

The stomach is generally described as being divided into two separateautonomic parts—the upper, proximal or fundus, and the lower, distal orantrum. The upper (proximal/fundus) stomach distends on the entry offood, as well as acting as a food reservoir and as a pump that pushesthe liquids and gastric contents out of the stomach. The function of thelower (distal/antrum) stomach is to grind food down to smaller particlesand mix it with digestive juices so that it can be absorbed when itreaches the small intestine. The stomach also empties its contents intothe intestine at a controlled rate to avoid excessive delivery of foodor acids, which could damage or overload the small intestine.

Three types of movements can generally be discerned in the stomach:

-   1. Rhythmic, synchronized contractions in the lower part of the    stomach, at a rate of approximately 3 per minute, which create waves    of food particles and juice which splash against the closed    sphincter muscle (the pyloric sphincter) to grind the food down into    small particles.-   2. The upper part of the stomach shows slow relaxations lasting a    minute or more that follow each swallow and that allow the food to    enter the stomach maintaining constant pressure while volume is    changing; at other times the upper part of the stomach shows slow    contractions creating a gradient in pressure, which help to empty    the stomach.-   3. Between meals, after all the digestible food has left the    stomach, there are occasional bursts of very strong, synchronized    contractions that are accompanied by opening of the pyloric    sphincter muscle. These are sometimes called “house-keeper waves”    because their function is to sweep any indigestible particles out of    the stomach. Another name for them is the migrating motor complex.

As previously mentioned, the barostat method is invasive, uncomfortable,impractical for wide clinical use, and may not necessarily provideaccurate results. Furthermore, it is limited to determination ofdistension and filling disorders of the stomach alone, and other testsneed to be applied for other disorders manifesting themselves in the GItract, such as those generically related to transit time ormalabsorption, or those called IBS disorders. The widespread prevalenceof such gastric and GI malfunction makes it important to have a simple,quick, easily tolerable and reliable test for diagnosing anddiscriminating between various forms of such disorders.

The above-referenced book by C. Stendal is particularly useful as areview of the background of the subject matter of this application. Thedisclosures of each of the publications mentioned in this section and inother sections of the specification, are hereby incorporated byreference, each in its entirety.

SUMMARY OF THE INVENTION

The present invention seeks to provide new apparatus and kits for use inimplementing novel methods, that allow a more exact diagnosis of gastricdisorders in patients that suffer from dyspepsia or IBS, as well as inasymptomatic patients that are in risk groups. In particular, methodsare proposed that allow a more exact diagnosis by means of dedicatedbreath tests for GI disorder determination. When these methods areimplemented in the form of breath tests, they are also easily toleratedby the patient, and sufficiently simple that they can be performed bymedical technicians, in contrast to many of the prior art tests forgastric disorders, which could be performed only by medical doctors. Anautomated breath tester which provides real time results, such as thatdescribed in U.S. Pat. No. 6,186,958 for “Breath Test Analyzer”,assigned to the assignee of the present invention, not only make thetests quicker, but also is almost essential for enabling the practicalexecution of some of the methods of the present invention, where almostcontinuous, on-line monitoring of the results enables the tests to becompleted sooner than in prior art methods where the provision of realtime results is not feasible. However, the apparatus of the presentinvention, at least for implementing the methods of the presentinvention relating to gastric emptying and gastric accommodation, canalso be of other types capable of following the gastro-intestinalprogress of a meal. Other such types of apparatus for breath analysis,include isotope ratio mass spectrometers and others. Other types ofinstruments unrelated to breath tests, include an MRI imager, aComputerized Tomography System, a scintigraphic imager (a gamma camera),an X-ray apparatus, an ultrasound imager, or others, as described below.However, except where otherwise noted, and in order to simplify theapplication, the apparatus generally used to describe the variousembodiments of this invention is a breath test apparatus.

In addition, the preferred methods and apparatus of the presentinvention allow control management of the treatment of such patients.The significant clinical advantage of these methods is clear, due torecent research work that shows that GI patients often have symptomsthat are not stable; therefore treatment according to symptoms only,without ongoing testing, may be problematic.

The disorders that can be diagnosed and followed by the preferredmethods and apparatus of the present invention can be divided into twogroups:

-   -   (A) Dyspepsia-type disorders, generally related to feelings in        the region of the stomach, including

(i) delayed gastric emptying;

(ii) disturbed gastric accommodation;

(iii) the effects of Helicobacter pylori infection; and

(iv) gastric chemical sensitivity or sensation.

-   -   (B) Irritable Bowel Syndrome type disorders, including:

(v) bacterial overgrowth;

(vi) lactose intolerance; and

(vii) orocecal transit time disorders.

The assessing of different physiological findings for dyspepsia, allowsthe prescription of the appropriate therapy. For example, a patient withdelayed gastric emptying and normal gastric accommodation can be treatedwith pro-kinetic therapy (including pharmacological agents, diet). Inanother example, a patient with abnormal gastric accommodation and apositive urea breath test for H. pylori, can be treated for H. pylorieradication alone or in combination with a fundus-relaxing drug.

There is further provided in accordance with yet another preferredembodiment of the present invention a set of at least one meal, at leastone meal of the set comprising at least one constituent operative tocause retention of the at least one meal in the stomach of a subject,and having a predetermined volume, for use in determination of gastricaccommodation of the subject by means of at least two measurements of agastric emptying parameter of the at least one meal as a function of thevolume of the meal having exited the stomach of the subject. Preferably,the at least one meal is one meal, and the at least two measurements areperformed on the one meal. Furthermore, at least one of the at least twomeasurements is performed on a liquid emptying phase of the meal fromthe stomach of the subject. Additionally, the at least one meal is atleast two meals, and one of the at least two measurements is performedon a first one of the at least two meals, and a second one of the atleast two measurements is performed on a second one of the at least twomeals. The first one of the at least two meals may be larger than thesecond one of the at least two meals, or smaller.

In the above-mentioned preferred embodiments of the present invention,the predetermined volume is at least 150 milliliters, and at least onemeal of the set comprises a marker which is detected after leaving thestomach of the subject. This marker may preferably be detected by itspresence in the exhaled breath of the subject, or within the body of thesubject, in which case it may be preferably detected by its presence inthe gastro-intestinal tract of the subject.

In the above mentioned embodiments of the present invention, at leastone meal of the set preferably comprises at least one of:

-   -   a caloric value of at least 150 kcalories,    -   a lipid content of at least 5%,    -   a carbohydrate content of at least 10%,    -   a protein content of at least 5%, and    -   a pH value of less than 3.        The carbohydrate may preferably be glucose.

In accordance with yet another preferred embodiment of the presentinvention, there is provided a single-dosage liquid meal for use by asubject in a breath test, comprising,

-   (i) a volume of at least 500 milliliters,-   (ii) an agent causing gastric retention of the meal, and-   (iii) a marker, stable in the gastric environment, and detectable    upon exiting the stomach of the subject.

The agent causing gastric retention of the meal may preferably compriseat least one of:

-   (i) a caloric value of at least 150 kcalories,-   (ii) a lipid content of at least 5%,-   (iii) a carbohydrate content of at least 10%,-   (iv) a protein content of at least 5%, and-   (v) a pH value of less than 3.

There is further provided in accordance with yet another preferredembodiment of the present invention apparatus for determining thegastric accommodation of a subject, following sequential administrationto the subject of a first and a second meal, at least one of the mealscomprising a marker detectable upon exiting the stomach of the subject,the apparatus comprising:

a detector for detecting the marker upon exiting the stomach of thesubject, and providing a marker output signal conveying informationabout the rate of emptying of the meal from the stomach of the subject,and

a data processing system-receiving the marker output signal andcalculating a first set of parameters which characterizes the gastricemptying of the first meal, and a second corresponding set of parameterswhich characterizes the gastric emptying of the second meal, and whichdetermines the gastric accommodation by comparing two correspondingparameters from the first and the second sets of parameters. In usingthis apparatus, the first and the second meals may be of differentvolumes, in which case the gastric accommodation is determined from thedependence of the parameters on the volumes of the first and secondmeals. Alternatively and preferably, the first and the second meals maybe of similar volumes, and the second meal is administered before thefirst meal has emptied from the stomach of the subject.

In any of the last mentioned apparatus embodiments, the processingsystem may preferably be such as to compare a set of parameters of thesecond meal before the first meal has emptied from the stomach of thesubject. Furthermore, the marker is preferably detected by its presencein the exhaled breath of the subject or within the body of the subject,and if so, preferably by its presence in the gastro-intestinal tract ofthe subject.

In the above mentioned apparatus, the set of parameters calculated bythe processing system preferably comprises at least one of t_(1/2),t_(lag), GEC, CPDR, and the integral under a plot of the DoB as afunction of time.

In accordance with still another preferred embodiment of the presentinvention, there is provided a kit for the diagnosis of gastricaccommodation in a subject, comprising:

-   (i) a quantity of material for marking a first meal having a first    predetermined volume and a first predetermined gastric retention    characteristic,-   (ii) a quantity of material for marling a second meal having a    second predetermined volume and a second predetermined gastric    retention characteristic, and-   (iii) a protocol providing information relating to the preparation    of the first meal and of the second meal,    The protocol may also preferably provide information relating to the    administration of the first and the second meals to the subject, and    may also provide information relating to the point in time when the    second meal is taken, according to the results of gastric emptying    measured on the first meal. The kit may also comprise the material    necessary for the preparation of at least one of the meals, and also    may include a breath collecting device, which is generally a    disposable device.

There is further provided in accordance with still another preferredembodiment of the present invention, a breath test apparatus fordetermining at least one gastro-intestinal condition in a subject,comprising:

-   (i) a breath collection device for collecting breath from a subject    after ingestion of a marked substrate, and-   (ii) a gas analyzer for detecting the products of the marked    substrate in the exhaled breath of the subject,    wherein the breath test apparatus and the marked substrate are    adapted to perform a first breath test selected from a group of    possible breath tests providing gastro-intestinal information    related to the subject, and wherein the breath test apparatus and    the marked substrate are also adapted to perform at least a second    breath test selected from the group of breath tests, according to    the outcome of at least the first breath test, such that a    gastro-intestinal condition of the subject is determined from the    outcome of at least one of the breath tests.

In this breath test apparatus the gastro-intestinal condition maycomprise at least one of dyspepsia and irritable bowel syndrome, and thedyspepsia may be such that arises from at least one of a gastricemptying disorder, a gastric accommodation disorder, and a Helicobacterpylori infection. Additionally, the irritable bowel syndrome may arisefrom at least one of a sugar malabsorption disorder, a bacterialovergrowth, and an orececal transit time disorder. In such a case, thesugar malabsorption disorder is at least one of lactose intolerance,fructose intolerance, sucrose intolerance and maltose intolerance.

In accordance with a further preferred embodiment of the presentinvention, there is also provided a breath test apparatus for thedetermination of gastric emptying of a subject, comprising:

-   (i) a gas collector, for collecting exhaled breath samples from the    subject after administration of a test meal comprising a marker,    whose by-products are exhaled in the breaths of the subject in    accordance with the rate of emptying of the marker from the stomach    of the subject,-   (ii) a gas analyzer for analyzing the collected exhaled breath,    wherein the analyzing is performed essentially continuously, and-   (iii) a computing system which calculates, as the breath test    proceeds, at least one of the t_(1/2), t_(lag), delta over baseline    (DoB) curve amplitude, the integral under the plot of the DoB as a    function of time, and Gastric Emptying Coefficient (GEC) parameters    of the subject,    wherein the breath test apparatus provides an indication of a    gastric emptying disorder by determining a final estimated value of    at least one of the parameters, and determining whether the    parameter departs significantly from known norms for the value of    the parameter. This apparatus is preferably such that an indication    is provided of a gastric emptying disorder in the subject while the    subject is still providing breath samples to the analyzer, or    alternatively and preferably, in accordance with the on-going    analyses of the breaths of the subject.

There is also provided in accordance with yet a further preferredembodiment of the present invention, a substrate for isotopic breathtests, comprising an isotopically labeled material in amicro-encapsulated coating material, wherein the properties of themicro-encapsulation coating material are chosen such that theisotopically labeled material is released in a predetermined part of thegastro-intestinal tract. The micro-encapsulation coating material ispreferably chosen such that it breaks down and releases the isotopicallylabeled material according to the pH value of the environment throughwhich it is passing. Alternatively and preferably, the material is suchthat it breaks down and releases the isotopically labeled material onlyafter leaving the stomach of a subject. In the latter case, theisotopically labeled material may be used as a marker for determiningpassage through the duodenum. In accordance with further preferredembodiments of the present invention, the micro-encapsulation coatingmaterial is chosen such that it breaks down and releases theisotopically labeled material under the effect of enzymic action arisingfrom the enzymic environment through which it is passing. The enzymesmay preferably be those secreted by at least one of the pancreas and thegall bladder, such that the isotopically labeled material is used as amarker for determining passage through the duodenum.

In general, the micro-encapsulation coating is preferably such that itcan be more readily bonded to an administered meal than the isotopicallylabeled material itself.

There is even further provided in accordance with a preferred embodimentof the present invention, a set of a first and a second liquid meal foruse in determining the gastric accommodation of a subject, the firstliquid meal comprising a first predetermined volume, and the secondliquid meal comprising a second predetermined volume greater than thefirst predetermined volume and having a predetermined gastric retentioncharacteristic, wherein the second liquid meal is administered to thesubject after the first liquid meal has begun emptying from the stomachof the subject, and wherein the gastric accommodation of the subject isdetermined according to the deviation between a measured rate ofemptying of the second meal and a measured rate of emptying of the firstmeal. Preferably, the second predetermined volume is sufficient to causegastric distension in the subject, and may preferably be at least 500milliliters of liquid. In the above-mentioned sets of meals, the gastricretention characteristic may be such as to arise from at least one of apredetermined pH, a predetermined calorific value and a predeterminedcomposition of the second liquid meal. The predetermined pH ispreferably less than 3.0, the predetermined calorific value ispreferably at least 150 kilocalories, and the predetermined compositionis preferably an isotonic composition. The second liquid meal ispreferably administered as soon as the rate of emptying of the firstmeal from the stomach of the subject is determined, or may beadministered after a time when essentially all physiological effects ofthe first meal on the subject have terminated. Alternatively, the secondliquid meal is administered on a successive day to the first meal.Furthermore, the rate of emptying may be determined by any of a breathtest, scintigraphy, an X-ray, computerized tomography, gamma imaging oran ultrasound method.

There is also provided in accordance with a further preferred embodimentof the present invention a liquid meal comprising a predetermined volumeand having a predetermined gastric retention characteristic, for use indetermining the gastric accommodation of a subject, wherein the averagegastric emptying rate of the meal for a large plurality of normalsubjects is known, and wherein the rate of emptying of the meal from thestomach of the subject is measured, and wherein the deviation betweenthe rate of emptying of the meal from the stomach of the subject and theaverage rate of emptying of the meal for a large plurality of normalsubjects, provides an indication of the gastric accommodation of thesubject. Preferably, the predetermined volume is sufficient to causegastric distension in the subject, and may be at least 500 millilitersof liquid. In the above mentioned liquid meal, the gastric retentioncharacteristic may arise from at least one of a predetermined pH, apredetermined calorific value and a predetermined composition of theliquid meal. The predetermined pH may be less than 3.0, thepredetermined calorific value may preferably be at least 150kilocalories, and the predetermined composition is preferably anisotonic composition. Furthermore, the rate of emptying may bedetermined by any of a breath test, scintigraphy, an X-ray, computerizedtomography, gamma imaging or an ultrasound method.

In accordance with yet another preferred embodiment of the presentinvention, there is provided an isotopically labeled liquid meal,comprising a predetermined volume and having a predetermined gastricretention characteristic, for use in determining the effect of thevolume of a meal on the intragastric pressure of a subject, wherein therate of emptying of the meal from the stomach of the subject isdetermined by means of a breath test performed to detect isotopicallylabeled products of the meal in the breath of the subject, for meals ofvarying predetermined volumes.

There is further provided in accordance with yet another preferredembodiment of the present invention, a meal administered to a subject,for use in the determination of gastro-intestinal disorders in thesubject, the meal comprising at least a first and a second markermaterial, the first material being such that it is not generallyabsorbed in the subject's stomach, and releases a predefined gas in thepresence of intestinal bacteria, and the second material being such thatit indicates a location of the meal within the gastro-intestinal tractof the subject, and wherein the generation of the predefined gas in thesubject is detected by means of a breath test, and the position withinthe subject's gastro-intestinal tract at which the predefined gas isgenerated is determined by means of the second marker material. In theabove-mentioned meal, a by-product of the second marker material mayalso be detected by means of a breath test, such that the position ofthe predefined gas generation in the gastro-intestinal tract of thesubject is determined by the temporal relationship between theappearance of the predefined gas and of a by-product of the markermaterial in the subject's breath. The second marker material ispreferably labeled with a carbon isotope, and the by-product isisotopically labeled carbon dioxide. Furthermore, the first material maypreferably be a sugar metabolized in the small intestine of the subject,such that the time of detection of the predefined gas relative to thetime of detection of the second marker material is used to determine thepresence of bacterial overgrowth in the small intestine. In this case,the second material may also be a labeled sugar, also metabolized in thesmall intestine of the subject, such that the generally concurrentappearance in the breath of the subject of the predefined gas and aby-product of the second marker material may be indicative of thepresence of bacterial overgrowth in the subject. Additionally, thesecond material may be a labeled sugar also metabolized in the smallintestine of the subject, such that the appearance in the breath of thesubject of a by-product of the second marker material significantlyprior to the appearance of the predefined gas may be generallyindicative of the absence of bacterial overgrowth in the subject. In theabove-mentioned meals, the first material is preferably at least one ofglucose and lactulose. The second material may be at least one oflabeled sodium acetate, sodium octanoate, glucose, an acetyl leucineprobe, or a microencapsulated labeled substrate.

In any of the above-mentioned meals, the first material is preferably asugar generally metabolized in the small intestine of the subject, suchthat detection of the predefined gas essentially concurrent withdetection of a small quantity of the second marker material may be usedto determine the orocaecal transit time of the subject. Alternativelyand preferably, the first material is a sugar of a group thought to bemalabsorbed in the small intestine of the subject, such that it arrivesessentially unabsorbed at the colon of the subject, where the predefinedgas is generated by the presence of colonic bacteria, such that the timeof detection of the predefined gas relative to the time of detection ofthe second marker material may be used to determine a sugar intolerancein the subject. Also, the second material may be an isotopically labeledmaterial generally absorbed in the colon, such that detection of thepredefined gas essentially concurrent with detection of labeledby-products of the second marker material is used to determine a sugarintolerance in the subject. The second material may then be xyloselabeled with a carbon isotope, and the by-product is isotopicallylabeled carbon dioxide. Additionally, the second material may be anisotopically labeled material generally absorbed in the small intestine,such that the relative time and quantity of detection of the predefinedgas and labeled by-products of the second marker material is used todetermine whether the subject is suffering from one or both of a sugarintolerance and a bacterial overgrowth.

In accordance with still another preferred embodiment of the presentinvention, in the use of the above mentioned meals, the detection of asmall quantity of the predefined gas, characteristic of a small part ofthe first material in the presence of bacteria, occurring essentiallyconcurrently with the detection of the labeled by-products of the secondmarker material is used as an indication that the subject is suffering abacterial overgrowth. The detection of the predefined gas later than thedetection of the labeled by-products of the second marker materialgenerally can be used to indicate that the subject is suffering from asugar intolerance. The detection of a large quantity of the predefinedgas, characteristic of the majority of the first material in thepresence of bacteria, occurring essentially concurrently with thedetection of the labeled by-products of the second marker material maypreferably indicate that the subject is suffering a sugar intoleranceand a bacterial overgrowth. In any of the above-mentioned meals, thesugar may preferably be at least one of the group consisting of lactose,fructose, maltose and sucrose. Furthermore, the predefined gas may behydrogen and/or methane.

In accordance with yet another preferred embodiment of the presentinvention, there is provided a breath test apparatus comprising:

-   (i) a breath sample input port for receiving exhaled breath from a    subject after administration to the subject of at least one meal, at    least one of the at least one meal comprising a marker detectable    upon exiting the stomach of the subject,-   (ii) at least one gas analyzer for detecting the marker in the    exhaled breath of the subject,-   (iii) a gastric function processing module, receiving information    from the at least one gas analyzer and determining at least one of    the gastric emptying rate and the gastric accommodation of the    subject,-   (iv) dyspeptic symptom input functionality, receiving information    from the subject about the level of dyspeptic symptoms perceived at    least upon administration of the first meal and the second meal, and-   (v) a gastro-intestinal diagnostic processor, receiving information    from the gastric function processing module and the dyspeptic    symptom input functionality, and providing an output indicative of    the visceral sensitivity of the subject.

In this breath tester, the at least one meal may preferably comprises atleast a first and a second meal, at least one of the meals comprising amarker detectable upon exiting the stomach of the subject

There is further provided in accordance with yet another preferredembodiment of the present invention breath test apparatus comprising:

-   (i) a breath sample input port for receiving exhaled breath from a    subject after administration to the subject of at least one meal, at    least one of the at least one meal comprising a marker detectable    upon exiting the stomach of the subject,-   (ii) at least one gas analyzer for detecting the marker in the    exhaled breath of the subject,-   (iii) a gastric function processing module, receiving information    from the at least one gas analyzer and determining the gastric    emptying rate and the gastric accommodation of the subject, and-   (iv) a gastro-intestinal diagnostic processor, receiving information    from the gastric function processing module and providing an    evaluation of at least two causes of functional gastro-intestinal    disorders in a single procedure.

In this breath tester, the at least one meal may preferably comprises atleast a first and a second meal, at least one of the meals comprising amarker detectable upon exiting the stomach of the subject

In accordance with still another preferred embodiment of the presentinvention, there is provided more breath test apparatus comprising:

-   (i) a breath sample input port for receiving breath from a subject    after administration to the subject of at least one meal, at least    one of the at least one meal comprising a marker detectable upon    exiting the stomach of the subject,-   (ii) at least one gas analyzer for detecting the marker in the    exhaled breath of the subject,-   (iii) a gastric function processing module, receiving information    from the at least one gas analyzer and determining at least one of    gastric emptying rate and gastric accommodation of the subject,-   (iv) dyspeptic symptom input functionality, receiving information    from the subject about the level of dyspeptic symptoms perceived at    least upon administration of the first meal and the second meal, and-   (v) a gastro-intestinal diagnostic processor, receiving information    from the gastric function processing module and the dyspeptic    symptom input functionality, and providing an evaluation of at least    one cause of dyspepsia in a subject, the at least one cause being    selected from gastric accommodation, gastric emptying and visceral    sensitivity, in a single procedure.

In this breath tester, the at least one meal may preferably comprises atleast a first and a second meal, at least one of the meals comprising amarker detectable upon exiting the stomach of the subject

There is further provided in accordance with still another preferredembodiment of the present invention, a kit for use in a breath test forthe evaluation of at least one of the causes of dyspepsia in a subject,comprising:

-   (i) a first quantity of material for marking a first meal having a    first predetermined volume and a first predetermined gastric    retention characteristic,-   (ii) a second quantity of material for marking a second meal having    a second predetermined volume and a second predetermined gastric    retention characteristic, and-   (iv) a protocol providing information relating to the preparation of    the first meal and of the second meal,-   (v) wherein the breath test evaluates at least one of the causes of    dyspepsia in a subject selected from gastric accommodation, gastric    emptying and visceral sensitivity in a single procedure.

In the above-mentioned kit, the first predetermined volume and thesecond predetermined volume may preferably be different.

In accordance with a further preferred embodiment of the presentinvention, there is also provided a set of a first and a second meal foruse in determining at least two of gastric accommodation, gastricemptying and visceral sensitivity of a subject, the first mealcomprising a first predetermined volume, and the second liquid mealcomprising a second predetermined volume and having a secondpredetermined gastric retention characteristic,

wherein the second meal is administered to the subject after the firstliquid meal has begun emptying from the stomach of the subject, and

wherein the measured emptying rates of the first and second meal areutilized to determine the gastric emptying and gastric accommodationlevel of the subject, and

wherein dyspeptic symptoms of the subject are ascertained at least uponadministration of the first and the second meal, and

wherein the dyspeptic symptoms of the subject are correlated with thevolumes of the first and second meal to determine the level of visceralsensitivity, such that at least two of gastric accommodation, gastricemptying and visceral sensitivity of a subject may be determined in asingle procedure.

In the above-mentioned set of a first and a second meal the firstpredetermined volume and the second predetermined volume may preferablybe different.

There is provided in accordance with yet a further preferred embodimentof the present invention, a set of at least one meal, at least one mealof the set comprising at least one constituent operative to causeretention of the at least one meal in the stomach of a subject, andhaving a predetermined volume, for use in the determination of at leasttwo of gastric accommodation, gastric emptying and visceral sensitivityof a subject,

wherein the gastric accommodation and the gastric emptying aredetermined by making at least two measurements of a gastric emptyingparameter of the at least one meal as a function of the volume of themeal having exited the stomach of the subject, and

wherein dyspeptic symptoms of the subject are ascertained as a functionof the volume of the meal retained in the stomach of the subject todetermine the level of visceral sensitivity, such that at least two ofgastric accommodation, gastric emptying and visceral sensitivity of asubject may be determined in a single procedure.

In the above-mentioned set of at least one meal, the first predeterminedvolume and the second predetermined volume may preferably be different.

There is even further provided in accordance with a preferred embodimentof the present invention, a set of at least a first and a second mealfor use in making an evaluation of at least two causes of functionalgastro-intestinal disorders in a single procedure the first mealcomprising a first predetermined volume and having a first predeterminedgastric retention characteristic, and the second liquid meal comprisinga second predetermined volume and having a second predetermined gastricretention characteristic,

wherein the second meal is administered to the subject after the firstliquid meal has begun emptying from the stomach of the subject, and

wherein the measured gastric emptying rates of the first and second mealare utilized to determine the gastric accommodation of the subject, suchthat an evaluation of at least two causes of functionalgastro-intestinal disorders can be made in a single procedure.

Furthermore, in accordance with yet another preferred embodiment of thepresent invention, there is provided a set of at least one meal for usein making an evaluation of at least two causes of functionalgastro-intestinal disorders in a single procedure, the at least one mealcomprising a predetermined volume, and having a predetermined gastricretention characteristic,

wherein at least two measurements of the gastric emptying rate of the atleast one meal are performed as a function of the volume of the mealhaving exited the stomach of the subject, and

wherein the at least two measurements are utilized to determine thegastric accommodation of the subject, such that an evaluation of atleast two causes of functional gastro-intestinal disorders can be madein a single procedure.

There is also provided in accordance with a further preferred embodimentof the present invention, a set of at least a first and a second mealfor use in providing an indication of the visceral sensitivity of asubject, the first meal comprising a first predetermined volume andhaving a first predetermined gastric retention characteristic, and thesecond liquid meal comprising a second predetermined volume and having asecond predetermined gastric retention characteristic,

wherein the second meal is administered to the subject after the firstliquid meal has begun emptying from the stomach of the subject, and

wherein the measured gastric emptying rates of the first and second mealare utilized to determine the gastric accommodation of the subject, suchthat the gastric emptying and the gastric accommodation of the subjectare known, and

wherein information is provided by the subject about the level ofdyspeptic symptoms perceived at least upon administration of the firstmeal and the second meal, the information being correlated with thegastric emptying and gastric accommodation of the subject by means of agastro-intestinal diagnostic processor, such that an output indicativeof the visceral sensitivity of the subject is obtained.

In accordance with yet another preferred embodiment of the presentinvention, there is provided a set of at least one meal for use inproviding an indication of the visceral sensitivity of a subject, the atleast one meal comprising a predetermined volume, and having apredetermined gastric retention characteristic,

wherein at least two measurements of the gastric emptying rate of the atleast one meal are performed as a function of the volume of the mealhaving exited the stomach of the subject, and

wherein the at least two measurements are utilized to determine thegastric accommodation of the subject, such that the gastric emptying andthe gastric accommodation of the subject are known, and

wherein dyspeptic symptoms of the subject are ascertained as a functionof the volume of the meal retained in the stomach of the subject, theinformation being correlated with the gastric emptying and gastricaccommodation of the subject by means of a gastro-intestinal diagnosticprocessor, such that an output indicative of the visceral sensitivity ofthe subject is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description, taken in conjunction with thedrawings in which:

FIGS. 1A and 1B show schematic flow charts describing possible coursesof detection and treatment for asymptomatic patients belonging to a GIhigh risk group (FIG. 1A), or for patients with symptoms of dyspepsia orIBS (FIG. 1B); FIG. 1C is an alternative schematic diagram forillustrating a method of detection and treatment for patients suspectedof having any of the above-mentioned GI problems, showing the proposedtests organized in a parallel arrangement;

FIGS. 2A to 2D are a set of four graphs showing an example of the realtime progress of the calculated t_(1/2), t_(lag), DoB and GEC gastricemptying parameters of a subject, as a function of time in hours, andFIG. 2E is a schematic representation of a preferred breath testapparatus, for obtaining and using this data to determine the normalcyof these parameters in a subject;

FIG. 3 is a schematic drawing of a curve of the DoB or of the exhaleddose of labeled decomposition product obtained in a GEBT performed withan unlabelled second meal;

FIGS. 4A and 4B are typical DoB curves as a function of time, resultingfrom the two meal procedure; in FIG. 4A are shown results for a subjectwith a normal gastric accommodation function, while in FIG. 4B are shownresults for a subject with a gastric accommodation disorder;

FIGS. 5A to 5D, schematically illustrate systems, according to morepreferred embodiments of the present invention, for performing gastricfunctioning tests, and especially gastric accommodation tests; in FIG.5A, there is shown a block diagram of the component parts of a gastricaccommodation test system, while in FIG. 5B are shown examples of theoutput data obtained from the data processor of such a system; FIG. 5Cis a schematic illustration of a breath tester, constructed andoperative according to yet another preferred embodiment the presentinvention, which is capable of providing multi-functional gastricdiagnosis information to the physician, in addition to that related togastric emptying and gastric accommodation; while FIG. 5D shows aschematic representation of a preferred display output screen of asystem such as that in FIG. 5C;

FIG. 6 illustrates schematically how compensation is made in the secondmeal curve for residual parts of the first meal still residing in thegastro-intestinal tract, with isotopic ¹³C-cleavage products that havenot been exhaled by the lungs yet;

FIG. 7 is a table showing the deviation of the gastric emptyingparameters between a series of subjects, some showing abnormal gastricaccommodation and some being asymptomatic for two-meal and two-testprocedures;

FIG. 8 shows schematic test results of an asymptomatic subject,performing a two-meal test, with a high volume water meal as the secondmeal;

FIGS. 9A to 9C show schematic samples of gastric emptying curvesobtained from single meal tests. FIGS. 9A and 9B show curves obtainedfrom normal individuals after administration of low volume and highvolume liquid test meals respectively, while FIG. 9C shows a curveobtained from a subject with impaired gastric accommodation;

FIGS. 10A and 10B show schematic samples of gastric emptying curves fromsymptomatic subjects for the second day test. In FIG. 10A, a 200 ml.high caloric test meal is administered and in FIG. 10B, an 800 ml. highcaloric test meal is administered;

FIGS. 11 to 13 are schematic examples of curves obtained, each showingboth a hydrogen peak and an isotopically labeled carbon dioxide peak, toillustrate the results obtained from subjects with different IBSdisorders, including bacterial overgrowth and sugar malabsorbtions; and

FIG. 14 schematically illustrates a system, according to anotherpreferred embodiment of the present invention, for performing breathtests for the detection of bacterial overgrowth or various GIintolerances.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to FIGS. 1A and 1B, which illustrate schematicallya flow chart describing possible courses of detection and treatment forpatients with symptoms of dyspepsia or IBS, or asymptomatic patientsbelonging to a GI high risk group, as defined hereinabove. The flowchart is not intended to illustrate a definitive algorithm for acomprehensive diagnosis and treatment routine, but rather to illustratesome of the possible courses open to the treating physician, which canbe taken using the methods and apparatus of the preferred embodiments ofthe present inventions. Though the tests in the preferred methodsillustrated in FIGS. 1A and 1B are described as breath tests, it is tobe understood that they can be equally well performed by other methods,as described hereinbelow.

Reference is also made to FIG. 1C, which is an alternative schematicdiagram for illustrating a method of detection and treatment forpatients suspected of having any of the above-mentioned GI problems. Inthe flow chart of FIG. 1C, the proposed tests are organized in aparallel arrangement, such that the physician can perform the requiredtests in the order of the intensity or the urgency of the patient'ssymptoms. Thus, for example, a subject suffering from gastric refluxwould first be tested for H-p infection, and only if the test provednegative, or if the test were positive and the treatment did not providesymptomatic relief, would it be necessary to initiate another test otherthan that for H-p.

More detailed explanations are now presented of the methods of executingeach of the tests shown in FIG. 1B, according to the methods andapparatus of preferred embodiments of the present invention. Though ineach of the following sections, the tests are generally described interms of the procedures for breath tests, this being a particularlyconvenient way of executing the tests, it is to be understood that theycan be performed, where appropriate, by other methods and on otherapparatus, as described hereinbelow. Use of such alternative methods orsystems is particularly applicable to the gastric emptying test and thegastric accommodation tests, though the breath test may still be themethod of choice.

1. Breath Test For Helicobacter Pylori

The breath test for Helicobacter pylori infection is well documented inU.S. Pat. No. 6,067,989 for “Breath Test for the Diagnosis ofHelicobacter pylori in the Gastrointestinal Tract”, assigned to theassignee of the present application, and herein incorporated byreference in its entirety, and no further details are thereforepresented here of the test itself. The use and position of the test inthe diagnostic hierarchy of FIG. 1B is described above, and below inrelation to FIGS. 1C, 5C and 5D.

2. Gastric Emptying Breath Test (GEBT)

Symptoms related to delayed gastric emptying include nausea, vomitingand unstable glucose levels in diabetic patients. Poor emptying of thestomach can occur for several reasons:

-   1. The outlet to the stomach, including the pylorus and duodenum,    may be obstructed by an ulcer or tumor or by a large and    indigestible item that was swallowed.-   2. The pyloric sphincter at the exit to the stomach may not open    enough or at the right times to allow food to pass through. This    sphincter is controlled by neurological reflexes to ensure that only    very tiny particles leave the stomach and to limit the amount acid    or food that can leave the stomach at one time to enter the small    intestine. These reflexes depend on nerves which can sometime become    damaged.-   3. The normally rhythmic, 3-per-minute contractions of the lower    part of the stomach can become disorganized so that the contents of    the stomach are not pushed towards the pyloric sphincter. This also    usually has a neuropathic origin; the most common cause is    longstanding diabetes mellitus, but in many patients the cause of    delayed gastric emptying is unknown, so the diagnosis is given as    idiopathic gastroparesis.

Methods for the determination of gastric emptying of solids has beenpreviously developed using radio-isotopically labeled carbon substrates,in the field of scintigraphy. In such methodology, the progress in theemptying of the labeled substrate from the stomach is followed,generally by direct imaging of the radiation emitted from theradioisotope. Breath tests for measuring similar time parameters havebeen proposed, in which the progress in the emptying of the labeledsubstrate from the stomach is followed by observing the labeledby-products of the substrate exhaled from the subject's breath, ratherthan by measuring what is left in the patient's body. Prior art gastricemptying breath tests (GEBT) commonly classify patients as normal,slightly delayed and delayed, according to the test protocol used.

Prior art GEBT's are generally performed by administering, in most ofthe cases, a solid test meal of 150-350 kilocalories, with a substratelabeled with either C¹³ or C¹⁴ as a marker. Examples of such substratesare Octanoic Acid, Sodium Octanoate, Sodium Acetate or Acyl Amino Acidas Acetyl Leucine, and others.

The optimal characteristics of these substrates are:

-   1. Good bonding to the test meal and so unreleased in the gastric    environment;-   2. Rapid release from the test meal when it leaves the stomach;-   3. Immediate absorption, metabolization and conversion to measurable    CO₂;-   4. Dual usage for GEBT of liquids and solids for clinical    simplicity; and-   5. Easy preparation and reasonable cost.

Currently utilized substrates fulfill only some of thesecharacteristics. Octanoic acid can be firmly bonded after cooking to thesolid fats used in the meals. It is also quickly released from the foodwhen passing through the duodenum, but after being absorbed in the smallintestinal walls, it needs to be transported to the liver andmetabolized there to produce CO₂. These processes are not directlyrelated to the gastric emptying rate and can extend for a notinsignificant time beyond the gastric emptying time, and are thussources of delay in detecting the true gastric emptying rate.Furthermore, variability in the results may also be generated, since theCO₂ release is dependent on liver function, which may vary from subjectto subject. Thus for example, it has been noted that even temporaryimpairment of liver function resulting from the consumption of amoderate quantity of alcohol can affect such prior art gastric emptyingmeasurements for some time after the consumption, even though it wouldappear that the gastric emptying rate itself is probably unaffected bythe previous alcohol consumption.

In addition, octanoic acid handling requires special equipment and mealpreparation is unsuited and clumsy for performing in the clinicalsetting. Meal preparation outside the clinical setting, on the otherhand, has the disadvantage that regulatory approval is required for thewhole of the meal and for its manufacturing process, and not just forthe labeled substrate, as is commonly accepted in most breath tests.Therefore, such a procedure requires a high level of standardization andits associated costs are high.

Sodium octanoate is the sodium salt of octanoic acid. It is easier tohandle than the octanoic acid itself, and is released from solids afterleaving the stomach but it suffers from the same indirect metabolismpath as octanoic acid, and is not easily mixed homogeneously with asolid meal.

Sodium acetate is generally considered the optimal substrate for themeasurement of gastric emptying of liquids and semi-solids. This verysimple and low cost substrate is rapidly metabolized after passingthrough the duodenum and readily converted into CO₂. However, it iseasily diluted by water and acidic media, and in the gastricenvironment, is easily detached from its meal base, such that itsprogress does not necessarily reflect the emptying rate of the meal.Therefore it is clinically unpractical for use with solid meals.Furthermore, the need to bond it to a solid meal by industrial foodpreparation techniques gives it some of the disadvantages of octanoicacid.

Acyl Amino Acid as Acetyl Leucine has been recently proposed as analternative GEBT substrate, and does not suffer from most of thetechnical drawbacks of the octanoates related to bonding, metabolizationand versatility, but it is of higher cost. Furthermore, since it is nota naturally occurring substance, it may require a complex regulatoryprocess before approval for use.

Sodium bicarbonate has also been proposed as an alternative substratedue to its being a readily accessible and abundant source of CO₂, andbecause of its simplicity and low cost. However, it too cannot be easilybonded to food, and releases its CO₂ content too readily through thegastric walls, making it impractical to use.

A breath test using an encapsulated version of ¹⁴C-labeled sodiumbicarbonate was attempted by Zighelboim et al, as described in thearticle “Will a NaH¹⁴CO₃ capsule method accurately measure gastricemptying?”, published in Am. J. Gastroenterol. Vol. 88(3), pp. 462-4,March 1993. The test was unsuccessful, since the capsule used was biggerthan the 2 mm size of the particles that the stomach evacuates as“liquid” food and was not bonded to the meal. Gamma camera measurementsshowed that it remained in the stomach after the food had emptied.

In performing a GEBT, one breath sample is usually taken as a baselinebefore administration of the meal, followed by breath samples during 4hours usually taken every 15 min. The breath samples are analyzed bymeans of mass spectrometry, non dispersive infrared spectrometry, or anyalternative method of isotopic analysis. The rate of metabolization ofthe substrate is determined from the change in ¹³CO₂ exhalation (deltaover baseline—DoB) and the curve of the metabolized substrate excretiondetermined from the DoB as the Percentage Dose Rate (PDR) and expressedas:y=at ^(b)exp(−ct)  (1)

wherein a, b and c are parameters to be fitted according to themeasurement curve, such as by means of a least square fit, or bynon-linear regression analysis.

A cumulative curve of the substrate excretion is then computed from theintegral of the last curve asy _(c) =m(1−exp(−κt))^(β)  (2)and the parameters m, κ and β calculated by regression analysis. Inorder to derive these parameters an estimation of the CO₂ rate ofproduction is derived from the DoB, based on the height and weight ofthe subject being tested. This normalized rate of production is known asthe Percentage Dose Rate, PDR, and is more generally used than the DoBfor Gastric Emptying applications. The total dose emitted is also auseful measure in analyzing the gastric emptying function, and isobtained by integrating the PDR values, and is known as the CumulativePercentage Dose Rate, CPDR. The method of obtaining the PDR and CPDRfrom the subject's DoB, normalized according to the subject's weight andheight, is disclosed by Y. F. Ghoos et al in “Measurement of gastricemptying rate of solids by means of a carbon-labeled octanoic acidbreath test”, published in Gastroenterology, Vol. 104(6), pp. 1640-7,June 1993.

There are three traditional parameters, derived from a GEBT, whichdescribe the gastric emptying outcome of a patient.

-   1. The half emptying time (t_(1/2)) or the time in which half of the    test meal has left the stomach, computed by setting y_(c)=m/2, such    that t_(1/2)=−1/κ*ln(1−2^(−1/ββ)).-   2. The lag time (t_(lag)) defined as the time in which the emptying    of solid phase of food begins after the initial liquid phase    emptying, and given by t_(lag)=(ln β)/κ.-   3. The gastric emptying coefficient (GEC) equal to ln a. This    parameter is related to the amplitude of the substrate recovery    curve.

Preferred embodiments of the present invention relating to gastricemptying breath tests are now described. One of the advantages of themethods and apparatus of the present invention is the calculation andanalysis of any of the above parameters in real time while measuring anddetermining when there is enough data to distinguish between patientswith normal, slightly delayed and significantly delayed emptying. Thistherefore significantly shortens the time taken to achieve a definableresult, from the four hours currently needed by prior art methods, suchas using mass spectrometry measurements. Another significant advantageof the preferred embodiments of the methods and apparatus of the presentinvention is the possibility to follow changes in the dynamics of thegastric emptying, such as clearly identifying the peak or physiologynoise in the emptying process. Suitable devices and methods forperforming breath tests are described in the above-mentioned U.S. Pat.No. 6,186,958 for “Breath Test Analyzer”; in U.S. patent applicationSer. No. 09/542,768 for “Breath test Methods and Apparatus”, and in U.S.patent application Ser. No. 09/508,805 for “Isotopic Gas Analyzer”, allassigned to the assignee of the present application, and allincorporated herein by reference in their entirety. A breath testapparatus, according to a preferred embodiment of the present invention,for use in performing these tests for gastric emptying, is describedbelow in connection with FIG. 2E.

There are 3 stages in this procedure:

-   1, Determining normal and abnormal values, or ranges of values, of    t_(1/2), t_(lag), Delta over baseline (DoB) curve amplitude, and    Gastric Emptying Coefficient (GEC) parameters by accumulating data    from many test subjects.-   2. Testing a subject and monitoring, in real time, the calculated    t_(1/2), t_(lag), amplitude of DoB, and Gastric Emptying Coefficient    (GEC), as the measurement proceeds.-   3. Following the monitored graphs of these 4 parameters as they    progress during the measurement, and determining by means of    extrapolation at the earliest possible moment, a final estimated    value, within the allowed error limits, at which it can be    determined if one of the 4 parameters (t_(1/2), t_(lag), DoB or GEC)    is abnormal, or if they are all normal. The error allowed can be a    function of the estimated value obtained. When values are far from    the border between the normal or abnormal ranges, larger errors can    be tolerated than when borderline values are obtained.

As an example of the execution of this preferred procedure, table 1shows the results of testing a single subject four times byadministering 100 mg. of ¹³C-labeled octanoic acid and Acetyl Leucin asmarkers with a solid test meal of 150-350 kilocalories. The table showsthe times after the peak when each of the 4 parameters were extrapolatedto within 85% and 70% of their final asymptotic converged values.

TABLE 1 Estimated Time After Peak Necessary to Reach 85% & 70% Accuracyof GEBT Parameters (with extrapolation) for a Single Subject Time topeak t_(1/2) t_(1/2) t_(lag) t_(lag) GEC GEC DoB Test # (hours) 85% 70%85% 70% 85% 70% Amplitude 1 1.3 0.5 0.5 0.5 0.5 0.2 0.1 immediate 2 10.8 0.6 0.6 0.4 0.3 0.1 immediate 3 1 1 immediate 1 immediate 0.3 0.2immediate 4 1.3 0.7 0.3 0.7 immediate 0.1 immediate immediate

There are cases of subjects with rapid gastric emptying, in whom a highDoB amplitude may be obtained even before the peak is reached, asdetermined by comparison with the typical time taken to reach the peakand the DoB levels reached in a normal subject.

Reference is now made to FIGS. 2A to 2D, which are a set of four graphsshowing an example of the real time progress of the calculated t_(1/2)(FIG. 2A), t_(lag) (FIG. 2B), integrated marker exhalation as obtainedfrom the area under the DoB curve (FIG. 2C), and GEC (FIG. 2D) of achosen subject, as a function of time in hours. The results were takenusing a breath test apparatus shown schematically in FIG. 2E,constructed and operative according to a preferred embodiment of thepresent invention. The breath is collected and its isotopically labeledcontent analyzed preferably according to the methods shown in the breathtesters described in the above-mentioned patent documents. Curve fittingof the measured points to plots of the four gastric emptying parametersare preferably performed by means of a curve fitting algorithm, such asthe Levenberg-Marquat algorithm and using the Lab View program, suppliedby National Instruments Corporation, of Austin, Tex. 78759, U.S.A.,which is built into the data processor of the breath analyzer, which isshown in the preferred embodiment of FIG. 2E within the dashed lines.Initial guess values for the previously described coefficients a, b andc, are derived from the expected values of t_(1/2), t_(lag) and GECobtained from previous tests performed on the subject, or from anaverage of the normal ranges of these parameters from a large number ofpreviously measured normal subjects, as stored in a database module ofthe data processor. The values of these parameters are continuouslyextracted from the calculated curves derived from the measured breathes,and compared repetitively with the stored norm values in thedifferential gastric emptying parameter comparison module. By thismethod of real time measurement and almost continuous checking of themeasured curved for convergence to an asymptotic end value, the expectedvalues of the gastric coefficients can be anticipated to good accuracywell before the asymptotic end point of the curve has been reached. Adefinitive result can thus be generated by this apparatus significantlymore quickly than by prior art apparatus which does not providereal-time results of the breath test. In the example shown,extrapolation may be performed for the four gastric emptying parametersafter approximately 1 hour, which is significantly faster than would bepossible using prior art apparatus.

It is to be understood that the meaning of terms such as “virtuallycontinuously”, or “in real time”, when used in connection with breathsampling, is dependent on the test concerned. Thus, for a test lastingonly a few minutes, the terms may really mean non-stop sampling. On theother hand, for tests such as gastric functioning tests which may lastan hour or even more, samples taken periodically such as only every 10to 15 minutes, for instance, would still be regarded in the art as being“virtually continuously” sampled, and measured in “real time”, and areso described and claimed in this application.

Because there is sometimes no correlation between symptoms and delayedgastric emptying, the GEBT as described above is especially useful inthe periodic management of diabetic patients for insulin/drug-foodmanagement as discussed in Gastric emptying in diabetes: clinicalsignificance and treatment. Diabet Med., Vol. 19(3), pp. 177-194, March2002. In the case of dyspepsia, dyspeptic symptoms are the main reasonto test patients. It has been shown in the article by Maes B D, et al.,entitled “Gastric emptying rate of solids in patients with nonulcerdyspepsia” published in Dig. Dis. Sci., Vol. 42(6), pp. 1158-62, June1997, that delayed gastric emptying is not necessarily the origin of alldyspeptic symptoms, though first generation drugs for the treatment ofgastric emptying, such as Cisparide or Erytromycin, generally help toreduce dyspeptic symptoms. The effectiveness of new emerging medicines,such as the newly proposed Tegaserod, in relieving these symptoms is notclear enough yet, but since such drugs were designed to be more GIdisorder specific than those previously mentioned, diagnostic may berecommended before the drug is prescribed. This is especially importantdue to the fact that these drugs apparently treat the GI condition butdo not cure it, and have to be administered continually to treat thedisorder.

Other gastric motility disorders, related with visceral perception ofpain, early fullness and bloating, include manifestations of impairedgastric distention and accommodation, for which the proper treatmentincludes the administration of drugs to relax the muscular tone, such asGlyceryl Trinitrate, serotonigenic agents or some antidepressants.Currently barostat studies are the only clinical method in clinical useto measure these disorders.

According to the preferred embodiments of the present invention, thereis also provided a noninvasive, accurate and convenient method for themeasurement of the severity of these gastrointestinal conditions relatedto gastric emptying and other gastric motility disorders.

In addition, according to more preferred embodiments of the presentinvention, there is also provided a substrate for isotopic breath teststhat overcomes the disadvantages of the present available substrates.The substrate utilizes micro-encapsulated or an enteric coatedisotopically labeled material. The coating can preferably be an entericcoating that is broken down in the duodenum or the small intestine,rather than in the stomach, due to the higher pH in those parts of theGI tract, typically 6, compared with that in the stomach, typically 2.5to 3.5. Alternatively and preferably, a coating broken down by specificenzymes found only in the desired part of the GI tract can be used.

These capsules are preferably filled with ¹³C-labeled substrate of thesimplest materials, such as sodium bicarbonate or sodium acetate.Micro-encapsulation thus allows specific marker drug release of suchmaterials along the duodenum in a rapid and homogenous way, only afteremptying of the meal from the stomach.

Substrates such as octanoic acid are usually incorporated into egg yolkand an omelet is prepared therefrom as the test meal. It is know thatmicro encapsulation is produced during the meal cooking, since oils fromthe egg yolk form a hydrophobic coating around the octanoic acid andprotect it during the cooking process, providing its good bondingcharacteristics to the meal.

As previously mentioned, according to another preferred embodiment ofthe present invention, micro-encapsulation can be used wherein thecoating is decomposed by means of a selected enzymatic, rather than pHenvironment. The selectivity in this method relies on the presence ofspecific enzymes in the duodenum, such as those secreted by the pancreasor through the bile ducts. The advantages of this preferred embodimentare that it can be used for the micro-encapsulation for liquid meals,and also is not dependent on the variability of pH between subjects.

These preferred micro-encapsulated substrates have a number ofadvantages over prior art substrates, as follows:

-   1) Enablement of real time analysis of gastric emptying, since the    micro-capsules are homogeneously distributed in ingested food.-   2) Specific release of the substrate material, such as sodium    acetate or bicarbonate, in the duodenum or small intestine or colon,    in a rapid and homogeneous way, only after emptying from the    stomach. The release can be made pH dependent or specific enzyme    dependent. Furthermore, the absorption of the substrate can be    achieved without the need of an additional metabolic step.-   3) Possibility of using the same material for both solid and liquid    meals, since the bonding properties to food, the stability within    the gastric environment, the taste, the convenience of use, etc.,    are independent of the material itself, and dependent only on the    properties of the chosen micro-encapsulation coating.-   4) Enablement of the use of low cost ¹³C markers, while    micro-encapsulation itself is a reasonably low cost process, costing    in the region of tens to one hundred dollars per kilogram.    3. Test for Gastric Accommodation (GA Test)

An upper stomach with proper accommodation characteristics allows it tomaintain constant pressure while the volume increases. This part of thestomach is responsible for gastric emptying of liquids and has almost noeffect on gastric emptying of solids. The lower part of the stomach isnot thought to have a significant effect on gastric emptying of liquids.In addition it is known from the literature that excess intra-gastricpressure is related to upper gastrointestinal symptoms and thatinhibition of gastric emptying is required when high calorie meals areadministered.

There is therefore provided, according to yet more preferred embodimentsof the present invention, gastric accommodation tests (GAT) andapparatus for performing these tests, based on the principle that fordifferent distension volumes, the gastric emptying rate of liquids isunaffected in normal individuals, but is impaired for patients withimpaired accommodation.

Two methods for performing these GAT's are proposed, according todifferent preferred embodiments of the present invention. As previouslymentioned, these tests are primarily described in their breath testembodiment forms.

A. The Two Meal Method.

A low volume, preferably of the order of 100 ml to 350 ml, of a liquidmeal preferably containing a ¹³C-labeled substrate is administered tothe subject, in a similar manner to that known in prior art gastricliquid emptying breath tests, such as described by Mossi et al., inDigestive Diseases and Sciences, Vol. 39, No. 12, December 1994, Suppl.,pp. 107S-109S, incorporated herein by reference. A suitable ¹³C-labeledsubstrate may comprise, but is not limited to, octanoic acid, sodiumacetate, glucose, sodium octanoate, acetyl-leucine, Spirulina algae,micro-encapsulated bicarbonate or another substrate, preferablyundergoing direct and fast metabolism, which can be utilized for themeasurement of the liquid gastric emptying rate. The isotopic ratio inthe exhaled breath is measured at baseline and thereafter at regularintervals in real time. A Delta over Baseline curve is preferably tracedand a curve of the rate of liquid emptying or emptying from the stomachis determined from the outcome. A typical DoB curve as a function oftime, resulting from this procedure is shown on the left hand part ofFIG. 4A, and this is the typical shape of a normal gastric accommodationcurve.

According to a first method of these preferred embodiments of thepresent invention, a second liquid meal, preferably comprising at leastone of:

-   1) a high volume of water, typically from the order of 500 ml to 1.5    liter, or more;-   2) an isotonic solution;-   3) an acidic solution, such as one having a pH of 2.5 or lower; or-   4) a caloric liquid meal;    is administered to the subject to induce gastric distention, and/or    to limit the rate of gastric emptying. This second meal is    administered at time T_(o) as soon as enough data has been    accumulated from the first curve to evaluate the gastric emptying    rate of the first meal to the required accuracy, as described    hereinabove in the section on the breath test for gastric emptying    rate. T₀ is shown on the curve in FIG. 4A, and in those figures    thereafter where T₀ is indicated. The change in slope on the    emptying curve, or the change in the gastric emptying parameters,    such as t_(1/2) or t_(lag), is derived from the DoB plot. The    desirable characteristics of such a second liquid meal are at least    one of:-   1) having the effect of causing a distension effect in the proximal    stomach, or-   2) having a high caloric value or low pH value, so that inhibition    of gastric emptying is required to avoid over-loading of the small    intestine.    Therefore, one preferred and desired approach is to administer the    same liquid test meal as was administered in the first meal but with    a large amount of water, so as to induce stress of the fundus, and    thus to measure the emptying rate of meals of similar caloric    content but with different volumes. According to different preferred    embodiments, this second meal can be either with or without an    isotope labeled substrate. If no isotope labeled substrate is used    in this second meal, the effect of gastric accommodation of the    first meal is determined by means of the effect of the increased    volume of the second meal on the first emptying curve, if such an    effect is present. In this case, it is important that the second    meal be a low natural ¹³C source, so that it does not interfere with    the ¹³CO₂ levels generated from the metabolized ¹³C-labeled    substrate used in the first meal.

This effect is shown by reference to FIG. 3, which is a schematicdrawing of a curve of the DoB or of the exhaled dose of labeleddecomposition product obtained in a GEBT performed with an unlabelledsecond meal. At the time T₀, at which time the gastric emptyingparameters have been determined with sufficient accuracy, the secondmeal is administrated. The extrapolated shape of the curve beyond timeT₀, which would have been obtained without the administration of thesecond meal, is shown as a dotted line. The values of gastric emptyingparameters obtained from this curve are recorded as soon as available,i.e. close to or immediately after time T₀. Administration of the secondmeal may result in a change in the asymptotic tail end of the curve, asshown by the solid line. New values of gastric emptying parameters arenow calculated for this new curve, and the values compared with thegastric emptying parameters originally obtained from the initiallyobtained curve. In a normal subject, the values of gastric emptyingparameters will be little changed, if at all, while a subject withimpaired gastric accommodation will generally show noticeably changedvalues. In general, for the two meal tests, the level of gastricaccommodation impairment is defined by the detection of clinicallysignificant differences between corresponding sets of gastric emptyingparameters obtained from administration of the two meals. The extent ofsuch differences enable the detected gastric accommodation to becategorized as normal, abnormal or borderline.

In the case of an isotopically labeled second meal, the preferredprocedure is simpler and more direct, since a new curve can be modeleddirectly for the second meal and a new set of gastric emptyingparameters is calculated to determine the emptying rate of the secondmeal directly, as explained hereinbelow in connection with FIG. 4A andfollowing. The effects of the second meal on the emptying curve dependupon the composition of the meal. In a normal subject, the second liquidmeal does not generally significantly affect the shape of the secondemptying curve, which has a normal shape, similar to that of the firstmeal, as shown by the similarity of the two curves shown in FIG. 4A. Thefirst meal shown in the example plotted in FIG. 4A was of 200 ml. ofEnsure Plus®, with 100 mg. of ¹³C-sodium acetate added thereto. Thesecond meal was 200 ml. of Ensure Plus® with 600 ml of additional water,and 100 mg. of ¹³C-sodium acetate added thereto. The quantity of labeledisotope added to the meals of the various preferred embodiments of thepresent invention are all given as 100 mg., though it is to beunderstood that this quantity could be varied according to the type oftest, the subject or the type of meal.

On the other hand, in subjects with some forms of gastric accommodationdisorder, a possible outcome of the breath test conducted according tothis preferred embodiment, would be to change the shape of the emptyingcurve on administration of the second meal, as typically shown in FIG.4B. In the example brought in FIG. 4B, using the same meals as thoseused in the test illustrated in FIG. 4A, it is observed that the gastricemptying is significantly quicker for the second meal than for thefirst. For the subject tested in FIG. 4B, for instance, t_(1/2) wasfound to be 174 minutes for the first meal (200 ml) and only 112 minutesfor the second, high volume meal (800 ml), thus showing that the subjecthas a significant gastric accommodation anomaly.

Reference is now made to FIGS. 5A and 5B. FIG. 5A a schematicrepresentation of a system, according to another preferred embodiment ofthe present invention, for performing the gastric accommodation tests asdescribed in the test methods above, and in FIG. 5B, are shown examplesof the output data obtained from the data processor of such a system,from which may be obtained indications of the presence or absence ofgastric accommodation problems in the subject.

Referring first to FIG. 5A, there is shown at the input, a meal sensor,which senses the test meal on leaving the stomach of the subject, andprovides a measure of the fraction of the marker (i.e. the test meal)expelled from the stomach or remained it the stomach as a function oftime elapsed from administration of the first test meal V1. This sensormay preferably be a breath test measurement relating to the PDR of themarker in the test meal on leaving the stomach, or any other sensorwhich is capable of plotting the progress of the marker from thestomach, such as MRI, scintigraphy (gamma imaging), CT, X-ray,ultrasound, or even such simple measurements as external volumetricmeasurements of the subject's abdomen to determine volume reduction ofthe stomach region.

The signal from the gastric emptying meal sensor is then preferablypassed to a meal sensor data analyzer, which analyzes the meal sensordata output and provides the necessary information concerning thepercentage meal expulsion from the subject's stomach as a function ofelapsed time, for further processing by the system. For a preferredembodiment in which the meal sensor is a breath test sensor, such a dataanalyzer could be a PDR curve generator, which takes into account thesubject's height and weight. At the same time, for a breath testapplication, the data analyzer could also continuously calculate theintegral under this curve and a CPDR plot against time is provided. InFIG. 5B, the intermediate results of these two plots are shown in thetop two graphs, designated 5B(i) and 5B(ii), which are generated by themeal sensor data analyzer.

Returning now to FIG. 5A, the analyzed data is now processed by the dataprocessing system, which may, for a breath test preferred embodiment ofthis invention, be similar to that shown within the dashed lines in therepresentation of the gastric emptying tester of FIG. 2E. The curvefitting module of the data processing system repeatedly attempts toobtain values of the parameters a, b and c of equation (1) above fromthe curves of the PDR or the DoB, and from the curves of the CPDR, oralternatively the integrated DoB, attempts are made to obtain values ofm, κ and β of equation (2) above. Once convergent values of theseparameters have been obtained, from the value of m, the parametert_(1/2) is computed, by setting y_(c)=m/2, as described above, and fromthe value of the parameter a, the value of the GEC, equal to log a, isobtainable. The value of t_(lag) is derived from t_(lag)=(ln β)/κ andcan be evaluated from the position of the peak of the curve afteradministration of the meal, as well. Other parameters which the dataprocessing system may generate for use in assessing the test results,are the integral area under the PDR Or DoB curves, indicating the totaldose detected, and the amplitude of the PDR or DoB curves.

It should be noted that since the gastric accommodation test isperformed on the same subject utilizing two consecutive meals withsimilar amounts of labeling material, the PDR curve can be replaced by aDoB curve for simplification. In this case the GEC does not reflect theactual GEC of the subject, and the actual CPDR is not computed. Thisvariance does not affect the outcome of the test because only thevariation between parameters is computed for test results on the samepatient, and not the parameters themselves as explained below. Otherparameters such as t_(1/2), t_(lag), the DoB amplitude and integralunder DoB curve are unaffected by this simplification.

In the bottom half of FIG. 5B, there are shown typical time plotsobtained from the output of the curve-fitting algorithm module of thedata processor, in which the calculated values of the gastric emptyingparameters GEC, t_(lag) and t_(1/2) are shown as a function of elapsedtime. These graphs are designated 5(iii), 5(iv) and 5(v) respectively.In each of the graphs, it is seen how the measured parameter convergeswith elapsed time to its final determined value. During the final stagesof convergence, the system is able retroactively to define an error bandaround the finally asymptotic end-value, and the processor is preferablyprogrammed to recognize this error band from the converging behavior ofthe curve. The width of the error band may preferably be determinedaccording to the result being obtained in real time. When it is apparentfrom the value of the parameter being plotted that the final value iseither clearly out of range of the norm, indicating clearly impairedgastric emptying, or well within the normal range, a wide error band isused, enabling the decision point about terminating that segment of thetest to be reached sooner. On the other hand, if the parameter seems tobe on the border line between normal and abnormal values, a narrow errorband is used in order to increase the final accuracy attainable for thatparameter.

Referring back now to the system of FIG. 5A, as soon as one, oraccording to another preferred embodiment, more than one of theparameters is detected as being confirmed as having entered the finalerror band, the system provides an output signal, either to the subjector to attendant medical staff, informing that the second meal of thegastric accommodation test should be taken by the subject. The systempreferably continues for a limited time to plot and calculate thegastric emptying parameters of the first meal, in order to increase theaccuracy of the values finally generated, since it takes some timebefore the effects of the second meal begin to appear at the mealsensor. This is particularly so when a breath test sensor is used,whereby commencement of detection of the second meal generally beginsonly when the meal begins to exit the stomach, or even some timethereafter because of the metabolic path delay time.

Once the second meal has been ingested, the gastric accommodation systemplots the progress of the second meal, in a similar way to which itmeasured that of the first meal, and a second set of gastric emptyingparameters are generated by the system, as shown in the bottom half ofFIG. 5A. However, the data processing system must utilize theextrapolated values of the PDR or DoB curve of the first meal forsubtracting from the PDR or DoB values of the second meal, as will beexplained hereinbelow in connection with FIG. 6.

Finally, once the data processor has determined that the second mealgastric emptying parameters have been obtained with sufficient accuracy,the system preferably compares corresponding sets of parameters from thetwo meals, and according to predetermined criteria, provides adiagnostic output about the presence or absence of impaired gastricaccommodation of the subject. According to one preferred criterion, thegastric accommodation is defined as being impaired if the value oft_(1/2) for the second meal is at least 10% less than that of the firstmeal, or if the value of GEC for the second meal is at least 5% morethan that of the first meal. Other preferred criteria relating to thedifference between the values of the amplitude of the peak of the PDRcurve or of the DoB curve for the two meals, may also be preferentiallyused, with an increase of more than 10% between the first meal and thesecond being considered as indicating impaired gastric accommodation.Alternatively and preferably, the integral areas under the PDR (i.e.CPDR) or the DoB curves can be the parameters used, with a 10% increasebeing defined as being indicative of impaired gastric accommodation.

According to further preferred embodiments of the present invention,combinations of parameters may be used for constructing the diagnosticcriterion, such that if a predefined number of the given parametersindicate impaired accommodation, then this is regarded as beingsufficient to make the diagnosis, even if other of the parameters do notshow significant differences. Furthermore, different parameters in thecombination used for the diagnostic criterion may be given differentweightings, such that those parameters which are more critical orindicative of the subject's gastric status are given more weight. Forexample, the half time may be given a higher weighting than the CPDR,thereby implementing an expert system into the apparatus capable ofproviding higher sensitivity and specificity to the procedure.

Reference is now made to FIGS. 5C and 5D, which are schematicillustrations of a breath tester, constructed and operative according toyet another preferred embodiment the present invention, which is capableof providing multi-functional gastric diagnosis information to thephysician. Such a system enables the physician to perform the diagnosticroutines illustrated in FIG. 1C, and even more, on a single instrument.The breath tester preferably both incorporates embodiments described inthe present application, and in addition, utilizes external inputs fromother tests to provide a comprehensive dyspepsia information managementsystem. FIG. 5C shows a schematic block diagram of the component partsof the breath tester, while FIG. 5D shows a schematic representation ofa preferred display output screen of such a system.

Reference is now made to FIG. 5C, which shows breath input I deliveringbreath, preferably in separate batches 1, 2, following theadministration of successive meals, for analysis by gas analyzer I,which preferably analyzes the breath for labeled carbon dioxide content.From here, the analysis results are directed to gastric emptying rateand gastric accommodation (GE/GA) diagnosis processing modules, such asthose shown in FIGS. 2E and 5A hereinabove. Additionally and preferably,the system also comprises a second gas analyzer II, which preferablyanalyzes the breath for hydrogen or methane content, and from where theresults are directed to a diagnosis processing module for the detectionof bacterial overgrowth, lactose intolerance, sugar malabsorption, orlow GI motility, such as that shown in FIG. 14 hereinbelow. Thisprocessing module is known as the IBS diagnostic generator. The outputinformation from the GE/GA and IBS diagnostic processors are input tothe multi-functional gastro-intestinal diagnostic processor, which isresponsible for sorting and assembling all of the output information forinputting to the display

Additionally and preferably, further inputs are provided to themulti-functional gastro-intestinal diagnostic processor from other testsproviding information about the subject's gastric condition. Amongstsuch tests are the results of a breath test for the detection of thepresence of a Helicobacter pylori infection. This test can be performedafter administration of the relevant labeled substrate for performingthe test, using the same breath input as for the GE/GA tests and thesame gas analyzer. However, to avoid interference with the results ofthe GE/GA tests, it should be performed at a different time to the GE/GAtests, preferably at least a few hours previously, and the resultsstored in the system memory.

Furthermore, the output from an electrogastrography (EGG) test can alsobe input to the processor and displayed on the display, such that thephysician also has these results for review in assessing the subject'soverall GI condition. In addition, an input of patient gastric symptomscan also be provided, as described in connection with the embodiment ofFIG. 5A. Finally, other external devices providing useful GI functionalinformation can also be input to the system, to provide as full apicture as possible for the physician.

Reference is now made to FIG. 5D, which illustrates a typical displayoutput screen of the system shown in FIG. 5C. In the preferred exampleshown in FIG. 5C, the screen is divided into two sections, with thegraphic outputs of the tests shown on the left hand side, and theresults of processing these graphic outputs displayed as a table on theright hand side, though it is to be understood that any other suitabledisplay arrangement may also be used without departing from the scope ofthe invention. There is shown a graphic outcome of a first low volumemeal, already extrapolated to show gastric emptying parameters afterconvergence is achieved, with a dashed line indicating the curvesextrapolated beyond the cut-off point of the test t₀. As is observed,the results of the first meal are plotted only until a clear indicationof the values of the first meal gastric parameters has been obtained.The bottom graph shows a second meal in which curve analysis is inprogress. The measurement curves for these two consecutive meals appearsimultaneously and separately together with an estimation of the dumpingcurves and an estimation of the gastric emptying rate from the firstmeal.

In addition, a graphic representation of the graded gastric symptomlevel of the subject, as expressed and input by the subject himself, isshown in the form of a histogram, as a function of time from the momentof meal ingestion. Assessment of gastric symptoms during meal ingestionis useful in determining a subject's visceral sensitivity, alsosometimes known as gastric sensation, which can determine whether thecause of the dyspeptic symptoms is related to the mechanical distresscaused by the meal volume, or to the chemical composition of the testmeal intake, such as for instance the fat content. Visceral sensitivityrelates to visceral sensory function, as described, for instance, onpage 27 of “Clinician's Manual on Managing Dyspepsia” by Gerald Holtmanand Nicholas S. Talley, published by Life Science Communications, 2000.In a sub-set of patients who suffer from functional dyspepsia adecreased threshold for perception of gastric distention has beenobserved. Therefore by comparing the symptoms of the subject, it ispossible to determine if the dyspeptic symptoms are associated withsensitivity to gastric distention or sensitivity to the chemical contentof the meal.

As an example, if a significant symptomatic reaction is observed duringthe ingestion of meals of different volume, it is a sign of chemicalcontent distress, regardless of whether the measurements also show agastric accommodation dysfunction related to the meal size. Thisinformation is of clinical importance in determining the appropriatepharmacological treatment. In the case shown in Fig. 5D, the gastricsymptoms recorded from the second and larger meal appear to be stronger,as often experienced with dyspeptic subjects who suffer from impairedgastric accommodation. This result is in-line with the faster emptyingof the second, high volume meal, which is indicated by the deviation insome of the gastric emptying parameters displayed.

Additionally, this system can also measure and display an excretioncurve of the hydrogen or methane level in the breath of the subjectrelative to the first and/or the second meal, as described in moredetail hereinbelow. At the top of one of the screens, an EGG trace isdisplayed for viewing by the physician, and the also results of aprevious test performed with the same system to detect activeHelicobacter pylori infection in the GI tract of the subject.

This single instrument, is thus able to perform a comprehensivegastro-intestinal monitoring procedure on a single platform, displayingresults for a number of functional GI disorders, and thus saving thesubject multiple visits to the doctor's office.

It is to be understood that the gastric emptying and gastricaccommodation breath tests described in the previously-mentionedpreferred embodiments may be preferably performed by any suitable breathtest apparatus, whether using an on-line, real time gas analyzer, orwhether the subject's exhaled breaths are collected in individual bagsand are then transferred to a remote gas analysis instrument, such as amass spectrometer. Furthermore, those of the methods which are amenablethereto, can also be performed using scintigraphy, gamma imaging, CT,conventional X-ray imaging, MRI, ultrasound, or any other means known inthe prior art for investigating and determining gastric functioning.

If breath tests are performed using an on-line, real-time breath testanalyzer, such as the BreathID apparatus supplied by Oridion MedicalLtd., or as described in the above mentioned U.S. patent documents, thenthe second meal can be administered to the subject at the earliestpossible time, either before the peak or after the peak, according tothe requirements of the test and the response of the subject. Use ofsuch apparatus thus may shorten the test in comparison with the otherpossible ways of applying the preferred methods of the present invention

According to one preferred procedure for applying this first methodusing an on-line breath tester, after measurement of the baselineisotopic level, the subject is given 100 mg. of ¹³C-sodium acetatedissolved in 200 ml of a standard high caloric liquid test meal, such asEnsure Plus®, or similarly available alternatives. Alternatively andpreferably, the ¹³C-sodium acetate can be pre-dissolved in 5 ml-15 ml ofwater to facilitate its incorporation into the caloric liquid meal.After meal administration, breath samples are collected and analyzed bythe breath analyzer at frequent intervals, or even quasi-continuously,and their DoB curve amplitude measured in real time, as described in theprior art. The resultant curve is fitted and extrapolated from themeasured points, as previously explained, and the gastric emptying rateparameters are computed in real time, as well as their convergencetowards their asymptotic values. A possible method to calculate theconvergence of the gastric emptying parameters is to plot them as afunction of time and to compute the derivative of the last measurementpoints, using the computing system that controls the breath analyzer, asdescribed in the above-referenced U.S. patent documents. When thederivatives approximate to zero the convergence of the parameters isachieved. The above mentioned point in time T₀ at which the second testmeal is administered, is assumed to be reached as soon as theconvergence of t_(1/2) and t_(lag) is decided as definitely known, sothat their values can be compared with those of the emptying curve ofthe second meal.

According to the preferred embodiment wherein the second meal is alsolabeled, the second meal also preferably comprises 100 mg. of ¹³C-sodiumacetate dissolved in 200 ml of a standard high caloric liquid meal, butdiluted with an additional 600 ml of water. The t_(1/2) and t_(lag)parameters are now calculated for the second test meal from the time T₀when it is administered. However, at least during the first period afteradministration of the second meal, a residual part of the first mealstill resides in the gastrointestinal tract, with its isotopic¹³C-cleavage products that have not been exhaled by the lungs yet. Theseresiduals from the first meal would therefore interfere with the resultsobtained from the isotopically labeled second meal. Reference is made toFIG. 6, which illustrates schematically how this physiologicalinterference is compensated for. As it is shown in FIG. 6, aftercomputing the shape of the first curve, and extracting from it values ofthe t_(1/2) and t_(lag) parameters for the low volume meal, the curve isextrapolated beyond the time τ₀ at which the second meal isadministered, and the residual values of the extrapolated curve aresubtracted from the measurement points to generate a correctedmeasurement curve from which the values of the t_(1/2) and t_(lag)parameters for the high volume meal are obtained. The actual measuredcurve is shown by the full line in FIG. 6, and the corrected curve bythe dotted line.

The deviation between the set of parameters of the first meal and of thesecond meal is calculated. In individuals with a gastric accommodationdisorder, the rate of emptying of the high volume second liquid meal isgenerally faster than for the first liquid meal. It is an indication ofincreased intra-gastric pressure, and therefore an indication of anaccommodation problem. In a number of analyses performed, the emptyinghalf-time of symptomatic patients was found to be at least 20% fasterfor the second meal. In addition, in these same test, a significantdecrease in T_(lag) (lag time) was observed in subjects with impairedaccommodation.

Reference is now made to FIG. 7, which is a table showing the deviationof the gastric emptying parameters between a series of subjects, someshowing abnormal gastric accommodation and some being asymptomatic.Results for the first method described hereinabove are shown on the lefthand half of the table, labeled “Two meal procedure”. These results arealso compared with those obtained from an alternative preferred method,called the “Two test procedure”, to be described hereinbelow.

It is seen that the lag phase deviation, expressed by the differences inthe t_(lag) parameter, is usually greater in symptomatic subjects. Highvalues of t_(1/2) and t_(lag) in the first meal are also an indicationof delayed gastric emptying.

In those embodiments where a high calorie liquid test meal is utilized,in a normal subject, a constant emptying rate is generally found,according to the rate of release of calories for passage to thedigestive tract. Especially suitable meals for this purpose are thosecaloric drinks with a high percent of fats, such as the commerciallyavailable Ensure Plus® or Nutradrink® products. Such a meal forces thestomach to release its caloric content slowly into the small intestine.It also allows the utilization of similar amounts of labeled substrate,independently of the dilution resulting from the different volumes ofthe test meals.

When only water is utilized as the test meal, using 200 ml and 800 ml ofwater each with 100 mg. of sodium acetate, for the first and second mealrespectively, the above-described tests lose some of their specificity.The test results of an asymptomatic subject, as shown in FIG. 8 indicatethat the t_(1/2) time after the high volume water meal was some 25%shorter than that after the low volume water meal, even though thesubject was known to be normal, and t_(lag) was unaltered. Afterperforming a similar test with low volume and high volume Ensure Plus®test meals, the same subject showed very close values for both t_(1/2),and t_(lag) for the two volumes.

When citric acid is utilized to modulate gastric emptying rate, asignificantly slower convergence of the parameters and also a lowerspecificity is generally found. This is thought to be because thephysiological mechanism of the stomach in releasing its contents as aresult of the pH of those contents is probably different from thecalorific emptying mechanism. Furthermore, pH is affected by dilution,while total calorie count is not. Therefore different test meals amountsmust be utilized for the different volumes.

According to further preferred embodiments of the present invention,there are provided kits for enabling the efficient and safe execution ofthe gastric accommodation tests of the present invention. In thepreferred case of a breath test, the kit preferably comprises therequired quantity or quantities of isotopically labeled marker materialfor adding to the meal or meals used in executing the test. In order toensure correct usage of the meals and marker, a directions-for-useprotocol (DFU) or a package insert is preferably included in the kit.This protocol can preferably include such instructions as the dilutionprocedures for the meals, if applicable, for the addition of the markermaterials, and instructions for identifying or relating to the point intime when the second meal is to be taken, either according to theresults of gastric emptying measured on the first meal, or where this isperformed automatically by the gastric accommodation test system,according to the signal provided by the system, or after apre-determined elapsed time, in those cases where the analysis is notdone on-line. This protocol can also preferably include directions forthe interpretation of the results of the test, which could preferably bethe criteria for defining a set of parameter results as being normal,abnormal or borderline, and/or differences in sets of parameters asbeing representative of patients with normal, abnormal or borderlinegastric accommodation, gastric emptying and visceral sensitivity.Alternatively and preferably, the kit could also include containers ofthe meal concentrates themselves, such as cans of Ensure® or the like,for producing the required meals by dilution. Alternatively andpreferably, the kit could also include a breath collection device usedfor collecting the subject's breath.

B. The Single Meal Method.

In this preferred embodiment, a single liquid meal with a definedcalorie content and containing a labeled marker preferably selected fromthose described above, is administered to the subject. The size of theliquid meal may preferably be 750 ml. or more, though as describedbelow, smaller meal volumes of down to 100 ml and larger meal volumes ofeven up to 1.5 liters, may be used. The meal is designed, for instanceby means of its low pH or its high calorific value, to ensure that itshould remain in the stomach of a normal subject for a certainpredetermined time x, such as 60 minutes, and have an emptying rate asdefined by the half emptying time, t_(1/2), of y, such as 90 minutes.Upon breath test analysis, a Delta over Baseline curve is preferablytraced and the curve of the liquid emptying though the stomach isdetermined from the outcome. The gastric emptying parameters aredetermined from this curve.

In subjects having a rate of emptying of the liquid meal faster thannormal, this may be an indication of increased gastric pressure, andtherefore an indication of an accommodation problem. A possible outcomeof the breath test would thus be a change in the slope of the emptyingcurve.

If results are not clear after this first test, the breath test may berepeated using the same meal but in a smaller volume, such as 100 ml,such that the meal is more concentrated. In this way, the effect ofvolume alone can be compared, as explained in the two test methodhereinabove. Samples of curves from normal individuals afteradministration of low volume and high volume liquid test meals are shownin FIGS. 9A and 9B respectively. As is expected from a subject withnormal gastric accommodation, the curve shapes are very similar, eventhough it is apparent from the dosage ordinate that the meal used inobtaining the results of FIG. 9B was significantly larger than that ofFIG. 9A.

The single meal breath test described above provides results either bycomparison of the extracted parameters with the accepted norms, or byrepetition and comparison with a different volume meal, which is thusessentially a two meal test. Reference is now made to FIG. 9C, whichshows the typical results from a further single meal test, indicative ofa third type of result from which information about gastricaccommodation disorders can be obtained. In this test, followingadministration of a high volume meal, such as that described in theembodiment of FIG. 9B, it is observed that the measured gastric emptyingrate is initially higher than normal, as evidenced by the large andearly peak of the dose curve. However, instead of a steady decline inthe detected meal volume expelled from the stomach, a second andgenerally lower peak is observed, which then often is seen to decay atthe expected normal rate as shown in FIGS. 9A and 9B. The result shownin FIG. 9C is typical of an impaired gastric accommodation conditionwhich causes the stomach to initially expel the large meal at a highrate, from which section of the curve a first set of gastric emptyingparameters can be extracted, typical of those pertaining to the largevolume of the meal in the stomach of a subject with impaired gastricaccommodation, and then, once the meal volume has reduced to lowerlevels, the gastric emptying becomes normal, and a second set of gastricemptying parameters can be extracted, typical of the small volumeremaining in the stomach. The difference between corresponding ones ofthese two sets of gastric emptying parameters can be used to determinethe presence and severity of the impaired gastric accommodation in thesubject. In this respect, the physiology of the subject's gastricemptying function is operative to turn a single meal test effectivelyinto a two meal test, since the gastric emptying function itself dividesthe meal emptying function into two separate phases, a high volume mealphase, and a low volume meal phase.

Similar results to those shown in FIG. 9C can be explained in terms ofan impaired gastric relaxation mechanism operative on reception of ahigh volume meal, this condition being known as abnormal gastricaccommodation reflex. In this condition, detection of two phases in thegastric emptying of a meal, and determination of the point in timebetween the phases may be used to indicate when stomach relaxationoccurs following meal administration. Delay in the stomach relaxationaccommodation process may indicate a pathological physiology function.It is to be understood, though, that the execution of this preferredembodiment of the present invention can be performed independently ofthe exact mechanism responsible for the resulting curve shape, and theactual or assumed mechanism is not meant to limit the scope of theinvention.

C. The Two Test Procedure.

In this preferred embodiment of the methods of the present invention,the tests are essentially the same as those described in the two mealmethod described above, but are preferably performed on two differentoccasions, at times sufficiently spaced apart that the effects of thefirst meal, including effects right down the metabolic pathway of thelabeled substrate, have essentially dissipated before the second meal isadministered. Typically, the two test method is performed on twosuccessive days, but where it is possible or desirable, a first testearly in the morning followed by the second test later in the day isalso an operable option. On each of these two separate occasions, a testmeal is administered with an identically labeled substrate, but with adifferent volume. The parameters of the normal ranges of gastricemptying and the test curves are determined and the relative deviationbetween the parameters of the curves for each measurement with itsspecific test meal volume are calculated. This approach may providegreater confidence than using one test, with one type of meal alone.

According to one preferred embodiment of the two-test procedure, thetests are performed on the subject on two different days. On the firstday, after a baseline isotopic breath measurement is taken, the subjectis administered 100 mg. of ¹³C-sodium acetate dissolved in 200 ml of astandard high caloric liquid test meal, such as Ensure Plus®.Alternatively the ¹³C-sodium acetate can be initially dissolved into 5ml-15 ml of water to facilitate its incorporation into the caloricliquid meal. After the meal administration, breath samples arerepeatedly or virtually continuously collected by a breath analyzer andtheir DoB measured in real time, as is known in the art. The measurementcurve is fitted to the results of the analyses, the gastric emptyingrate parameters are computed therefrom in real time, and theirasymptotic convergence values determined. On the second day, the sameprocedure is repeated, but the meal is amended, preferably by theaddition of 600 ml of water to the 200 ml of standard high caloricliquid test meal with 100 mg. of ¹³C-sodium acetate. The gastricemptying rate parameters are again calculated for this second meal, andtheir deviation from those of the first meal calculated. Some typicaltest results for a symptomatic subject are shown in FIGS. 10A and 10B.In FIG. 10A, a 200 ml. high caloric test meal is administered on thenext day to the same subject, and the value of t_(1/2) is found to be156 minutes. In FIG. 10B, an 800 ml. high caloric test meal isadministered, and the value of t_(1/2) is found to be 99 minutes,indicative of impaired gastric accommodation.

The above three described procedures have been described in terms oftheir implementation in the form of breath tests. However, it is to beunderstood that the concepts underlying the above-described methods forthe measurement of gastric emptying parameters could also be performedby using different measurement methods other than those of breathtesting. Such methods include, but are not meant to be limited to, theuse of radioactive isotope tracking using ⁹⁹Te, ¹⁴C or other labeledsubstrates, the use of ferromagnetic materials as markers to be trackedby MRI, the use of contrast materials in X-ray or CT methods, or the useof gas bubbles in ultrasound imaging, and alternative measurementmethods using such techniques as magnetic resonance, gamma imaging orscintigraphy. Each of these methods, as known in their respective arts,and including those described according to the present invention, ischaracterized by its own sensitivity, specificity and convenienceaccording to the meal utilized, population, clinical setting or themeasurement equipment utilized.

New mathematical methods to determine gastric emptying rate have beencurrently proposed as alternatives to those already described in “¹³C—Breath Test Modeling” by Tom Preston, East Kilbride. Department of ChildHealth and School of Veterinary Science, University of Glasgow. Thesemethods are based on coupling different differential equations, or theirequivalent, normalized to the Heaviside function, to each differentmetabolic or physiologic process, by means of a deconvolutive approach.Thus different parameters are obtained for each equation and arecombined to obtain t_(1/2) and t_(lag) or their equivalents. Thesecalculation methods differ from those known in the art only in theirmathematical approach, and are based on the same breath test proceduresor gastric emptying studies to provide an equivalent tool toscintigraphic analysis.

It has been observed in gastric accommodation procedures that the amountof labeled substrate does not affect parameters such as t_(1/2) andt_(lag), but only those related to the isotopic amplitude, such as theGEC, which shows mathematical homogeneity. It is therefore to beunderstood that the preferred methods of the present invention are notmeant to be limited to any specific method of calculation of the gastricemptying rate parameters, but are applicable to alternative mathematicalmodels also, such as that described above.

According to further preferred embodiments of the present invention, itis also proposed that it is of clinical significance to differentiatebetween either mechanical or chemical causes of dyspeptic symptoms inresponse to a meal. It is an objective of the present invention toprovide this indication by means of recording the symptomatic responseof the tested subject to the meals when the test is performed. Thus, inthe Two Meal Procedure and Two Test Procedure methods for investigatingpatients with suspected defective gastric accommodation, if discomfortsymptoms are observed only when a high volume test meal is administered,then the symptoms are an indication of a mechanical response to thevolume. When discomfort symptoms are recorded with the small meal, orwith both the small and the large meals, it is an indication of symptomsrelated to caloric or nutritional content or acidic composition of themeal, or what is termed “chemical stress sensitivity”. There existseveral methods to measure gastric discomfort symptoms, such as by theuse of symptom questionnaires, clinical observation, facial recognition,biofeedback, as are well known in the clinical arts. According to thesepreferred embodiments, a gastric symptomatic input can be entered intothe system, preferably according to a scale of subjective gastricsymptoms, with the recording being made after or during administrationof a small volume meal, such as 100 to 350 ml., and a large volume meal,such as 500 to 1500 ml. Correlation between the subjective gastricsymptom inputs and the objective gastric measurement outputs can then beperformed, to generate a more complete clinical assessment of thesubject's gastric accommodation, emptying and sensitivity.

These factors of gastric symptom can preferably be incorporated into thepreviously described systems, either by means of an input which isphysician generated from the results of a subject questionnaire, or bymeans of a direct patient input to the data processing system. Such agastric symptom input unit is shown in the apparatus depicted in FIG.5A, providing an additional input to the gastric accommodation, emptyingand sensitivity diagnostic output module. Since this is an optionalfeature, it is depicted in dashed outline.

Furthermore, according to another preferred embodiment of thisinvention, the above-described kit can preferably also include theelements of a questionnaire for applying to the subject, together withthe marker materials or the meals themselves, and either in addition toor as an alternative to the test protocol instructions.

By the incorporation of the above described features of the measurementof gastric emptying, gastric accommodation and visceral sensitivity inone instrument, there is thus provided, according to further preferredembodiments of the present invention, a system that enables, in a singleprocedure, the assessment and differentiation of the physiologicalcauses of dyspepsia in what is thought to be a majority of such cases. Asingle procedure is understood to mean, in relation to these preferredembodiments, a procedure that is performed on one day and using onesystem capable of correlating all of the data derived from the test. Theuse of such a single procedure thus removes day to day variability, andalso the need for multiple test procedures, often performed on separateinstruments. According to this preferred single procedure, successiveascertainments are made of the subject's dyspeptic symptoms atsequential times during passage of the meal through the subject'sstomach. An ascertainment can also be made before administration of themeal.

According to these preferred embodiments, there is provided a dyspepsiaevaluation breath test system, in which the gastric emptying, visceralsensitivity and gastric accommodation of a subject are accuratelydetermined in a single test. Using this system, the gastric emptying ispreferably determined from the first meal, the gastric accommodationfrom a comparison of the gastric emptying of the two meals, and thevisceral sensitivity is evaluated from correlation of the dyspepticsymptoms as reported by the subject, with the volume and progress of themeals at various stages of the test. According to further preferredembodiments of the present invention, and based on the embodimentsdescribed hereinabove relating to each of the three supposed causes ofthe dyspepsia, there are also provided kits, methods and meals, for usein the evaluation of overall dyspeptic malfunctions in subjects.

In addition, this procedure could be coupled with other alternativemotility parameters, such as an EGG, or physiological parameters such aslactose intolerance and bacterial overgrowth.

4. Bacterial Overgrowth Breath Test (BOBT)

Among other known causes of dyspepsia, IBS or gastrointestinal illnessare bacterial overgrowth, which is the colonization of the smallintestine or the upper gastrointestinal tract by colonic bacteria,lactose intolerance, malabsorptions of other sugars, or lowgastrointestinal motility. With respect to bacterial overgrowth, theassessment of the level of these microorganisms outside the largeintestine is usually performed either by means of gastroscopy, which iscumbersome, patient uncomfortable and depends on human interpretation,or by means of a hydrogen breath test (HBT). The HBT is performed byanalysis of the breath before and after administering to a subject of aquantity of a marker sugar, such as lactulose, which is not broken downin the stomach. Bacteria break down the lactulose to produce hydrogen, agas not produced by large organisms such as humans, as a natural resultof the lactulose metabolism. Thus an increase in hydrogen level measuredin the breath of a subject is an indication of bacterial activity. Thetime taken for the lactulose to reach the large intestine, as for othersugars which are not broken down in the stomach, is around 3 hours.Therefore an earlier hydrogen peak is a signal of bacterial overgrowth.Although hydrogen is the most common by-product used for breath testingof these GI disorders, methane can be produced when the ingestedlactulose is metabolized by an alternative or additional bacteriapresent in the small intestine. According to other preferred embodimentsof the present invention, such methane production can be used in thesebreath tests, in place of or in addition to hydrogen. Whenever thehydrogen breath test is mentioned in this application, it is to beunderstood that the test is meant to describe and to cover the methanebreath test also, the differences being generally only in the gasdetector used in the gas analyzer.

The main disadvantage of this prior art HBT is the need to identify theexact time during which the meal is passing through the small intestine.Because of variation in gastrointestinal transit times, both betweendifferent subjects and even in the same subject at different times,false negative and false positive diagnoses may arise.

Therefore to overcome these drawbacks, according to yet anotherpreferred embodiment of the present invention, a breath test is proposedin which a substrate is administered, containing not only a substancesuch as lactulose which generates hydrogen in the presence of bacteria,but also containing a second isotopically labeled marker which isoperative to indicate the location of the substrate within theintestinal tract. The hydrogen production is measured to indicate thefermentation action of bacterial flora, if any, and a second measurementof the decomposition products of the second marker is typically made atthe same time as the measurement of the hydrogen output. The secondmeasurement may preferably be the measurement of labeled CO₂ produced asthe result of metabolism by the subject of a labeled carbon-containingsubstrate.

According to a preferred embodiment of the present invention, a H₂detector such as an electrochemical spirometer or a gas chromatographeris incorporated in an isotopic gas analyzer being part of a breath testapparatus. Preferably, sample gases are collected in a control range ofCO₂ concentrations by means of an intermediate cell, as described in theprior art.

Several different types of substrate may preferably be used to checkboth H₂ production in the small or large intestine, and the passage ofthe substrate through the intestines. According to a first preferredmethod of performing this breath test, a relatively large amount ofglucose, lactose, sorbitol or lactulose, such as 100 g, are administeredto the subject, together with a relatively small amount of ¹³C-labeledsubstrate that is rapidly absorbed or metabolized by the body in theintestine such as 100 mg. of glucose or sodium acetate ormicroencapsulated bicarbonate, for measurement of labeled CO₂production. The glucose is absorbed and rapidly metabolized by thepatient's body only when it reaches the small intestine, at which pointit can be detected as labeled CO₂ in the subject's breath. The glucosecan also be metabolized by bacteria, which is detected as H₂ in thebreath. If the gaseous peaks of 13CO₂ and H₂ are correctly separated intime, in that the ¹³CO₂ peak occurs at least a predetermined time beforethe H₂, this indicates that the location of the subject's bacterialpopulation is normal. This situation is illustrated in the schematicbreath test results shown in FIG. 11. If, on the other hand, the H₂peaks at a time close to the ¹³CO₂ peak, it indicates the presence ofbacterial overgrowth in the small intestine, as shown schematically inFIG. 12. It should be noted that the “peak” of the hydrogen exhalationif far broader and long lasting than that of the ¹³CO₂ peak, andreferences to the H₂ peak as such, and its temporal position relative tothe ¹³CO₂ peak, and as claimed, are to be thus qualified. Indeed, inmost practical cases, instead of measurement of the “peak” position ofthe hydrogen, a measurement of H₂ exhalation is determined by theposition at which the hydrogen exhalation achieves a certain level abovethe baseline level.

In a normal individual, the glucose is absorbed and metabolized by thebody in the small intestine. Any remaining glucose will be available inthe large intestine to provide a detectable hydrogen peak upon bacterialmetabolism. In some instances, however, not enough glucose will remainto be passed to the large intestine to provide a detectable hydrogenpeak from bacterial metabolism in a normal subject. In this case, asugar which does not break down, such as lactulose, is included as atest substrate.

In another example, 100 mg. of a ¹³C labeled substrate is administeredtogether with a dedicated test substrate for a bacterial overgrowthhydrogen breath test, such as 10 grams of lactulose. As mentioned above,if the ¹³CO₂ peaks significantly before the H₂ this indicates that thelocation of the patient's bacterial population is normal, as shownschematically in FIG. 11. If the H₂ “peaks” at around the same time asthe ¹³CO₂ peak, it indicates the presence of bacterial overgrowth in thesmall intestine, as shown schematically in FIG. 13. In this example,however, the presence of a non-breakdownable sugar such as lactulose asa test substrate ensures that a hydrogen peak will be detected, whetherin the small intestine in a subject with bacterial overgrowth, or in thelarge intestine of a normal subject.

¹³CO₂ originating from the known metabolism of the ¹³C-labeledsubstrate, is a marker peak to determine the point which the meal hasreached in the gastrointestinal tract, and therefore, overcomesdifferences in digestion speed due to different metabolic dynamics, ordue to the clinical state of the subject. This preferred methodtherefore overcomes the prior art disadvantage of intra- andinter-patient variation in gastrointestinal transit times.

According to further preferred embodiments of the present invention, thejoint use of a hydrogen and a CO₂ marker in the ingested substrate alsoprovides a method to determinate accelerated or delayed orocecal transittime. This is the time between the oral administration of the food andits arrival at the colon, where the colonic bacteria ferment the sugars.This process could be characterized by a high peak of hydrogen with alow labeled CO₂ production.

Other alternatives tests meals include, but are not limited to, labeledsodium acetate, sodium octanoate, glucose, a probe such as acetylleucine, or a microencapsulated labeled substrate, together with arelatively large amount such as 70-100 g of unlabeled glucose, or 10 gof lactulose.

According to yet further preferred embodiments of the methods of thepresent invention, these substrates, provided in large amount, could beincorporated into a micro-encapsulation means, designed to allow theirrelease only in the alkaline intra-intestinal media. This enables animprovement to be achieved in the accuracy in time of the test.Alternatively, the two components can be provided separately in the samemeal, this being a particularly simple method of application. Singlelabeled substrates and dual/single microencapsulated markers have theadvantages over the prior art that the absorption and metabolization bythe body and/or bacterial fermentation are produced simultaneously inthe GI tract.

Alternatively and preferably a microencapsulated formulation, which isbreakdownable at the colon, containing a labeled substrate having rapidrelease, such as bicarbonate could be utilized to show orocecal gastrictime.

According to another preferred embodiment of the present invention,there is provided a method to improve the accuracy of and to shorten theduration of the lactose breath test (LBT), as well other sugarmalabsorption breath tests, such as fructose or maltose or sucroseintolerance. It is believed that lactose intolerance occurs in 25% ofthe general population and is characterized by the low availability inthe body of lactase, the enzyme which metabolizes the lactose in milkinto glucose and galactose, for utilization by the body. As aconsequence of this lactase deficiency, the unmetabolized lactose isfermented by colonic bacteria, producing detectable H₂. Simultaneousmeasurement of ¹³CO₂ and H₂ after ¹³C-lactose ingestion has beenproposed for diagnosing lactose-intolerance, to detect such absorptionof the unmetabolized lactose in the colon. Unfortunately, ¹³C-labeledlactose is expensive and not easily available, making this anunattractive method of testing. The production of naturally ¹³C-labeledlactose has been suggested, by feeding milk-producing cows with¹³C-enriched feed, which is reasonably cheaply available. However, theenrichment levels of such milk are too low to produce acceptable resultsand their variability is too high for standardization. There is thusprovided, according to another preferred embodiment of the presentinvention, a method of providing a dual meal for detecting lactoseintolerance. The dual meal comprises natural lactose, together with alabeled marker substrate, such as ¹³C-labeled xylose, a sugar which ismainly absorbed only when it gets to the colon, and which is readilyavailable at low cost. Thus after ingestion of the dual meal, if the¹³CO₂ is detected approximately at the same time as H₂, as shown in FIG.12, it is a sign that the lactose has not been absorbed in the smallintestine, due to the absence of lactase enzyme, but has reached thecolon together with the labeled lactulose. If on the other hand, no H₂is detected with the ¹³CO₂, this is a sign that the lactose has beencorrectly absorbed in the small intestine, and that the subject does notsuffer from lactose intolerance. Additionally, the use of this mealenables the test time to be shortened, since it is known that the H₂peak is expected shortly after the ¹³CO₂ peak if there is a deficiencyof endogenous lactase, such that there is no need to wait an extendedtime to see whether an H₂ peak appears or not.

According to yet another preferred embodiment of the present invention,a dual meal comprising lactose and a marker substrate absorbed in thesmall intestine, such as ¹³C-labeled sodium acetate, could be used todetermine the presence of either sugar malabsorption, such as lactoseintolerance or of bacterial overgrowth or of both. If the subjectsuffers from bacterial overgrowth but not from lactose intolerance, mostof the lactose is rapidly absorbed in the small intestine, but a smallquantity generates hydrogen because of contact with the bacterialovergrowth there. As a consequence, a small H₂ peak occurs approximatelyat the same time as the ¹³CO₂ peak as the meal is passing through thesmall intestine, as shown in FIG. 11. If on the other hand, the subjecthas lactose intolerance, then a large H₂ peak occurs when essentiallyall of the lactose reaches the bacteria in the colon, and this occurslater than the ¹³CO₂ peak, produced during passage of the labeled sodiumacetate through the small intestine, as previously explained. If thesubject suffers from both disorders, then the absence of a lactoseabsorption mechanism results in all of the lactose being available inthe small intestine for exposure to the bacterial overgrowth therein,and the result is a large H₂ peak occurring at the same time as the¹³CO₂ peak.

Alternatively a labeled substrate that is metabolized at the colon suchas xylose or microencapsulated bicarbonate could be utilized togetherwith the lactose. In such a case, an early hydrogen peak and a laterpeak of the labeled substrate is a sign of bacterial overgrowth. The twopeaks concurrently is a sign of lactose intolerance.

According to yet another preferred embodiment of the present invention,¹³C-labeled glucose, sodium acetate or another ¹³C-labeled material,could be utilized in a solid/liquid test meal including glucose orlactulose for the combined assessment of gastric accommodation, gastricemptying and bacterial overgrowth in one test at the same opportunity,thereby reducing the number of visits which the patient has to male tothe clinic.

The bacterial overgrowth breath test can be summarized as follows:

-   1. A meal is labeled with a ¹³C labeled material that is absorbed in    the small intestine and produces a CO₂ peak as soon as the meal    passes through the small intestine-   2. The same meal produces an H₂ peak in a Breath Test (BT) when it    gets to normal bacterial concentrations in the large intestines.-   3. The use of a non-broken down sugar, such as lactulose, determines    bacterial overgrowth according to the time taken for the H₂ peak to    develop.-   4. Perform the BT to detect both CO₂ and H₂ peaks. If the peaks are    correctly separated in time, the patient's bacterial location is    normal. If the H₂ peaks at a time close to the CO₂ peak, it    indicates the presence of bacterial overgrowth in the small    intestine.-   5. An advantage is that by using CO₂ as a marker peak to determine    the location of the meal in the GI tract, it is possible to overcome    differences in digestion speed due to different metabolisms, or to    the clinical state of the patient.

Reference is now made to FIG. 14, which is schematic representation of abreath test system for the detection of bacterial overgrowth, lactoseintolerance, sugar malabsorption, or low GI motility, constructed andoperative according to a preferred embodiment of the present invention.After administration of the relevant meal or portion containing thebreath test substrates, according to the particular test to be executed,as expounded in the above-described embodiments, the exhaled breaths ofthe subject are collected at the inlet to the system, and passed to dualgas analyzers. One of these analyzers is preferably of the type whichdetects and measures the quantity of hydrogen and/or methane in thebreaths, and the other is preferably an isotopic ratio analyzer, whichdetermines the ratio in the exhaled breaths of the labeled isotope fromthe ingested substrate to its equivalent naturally occurring isotope.These analyses are performed repetitively or even virtually continuouslyfor the duration of the test, and the results of each of these analysesare preferably input to a computing module which uses a curve fittingalgorithm, such as one of the numerous types known in the art, forfitting the data to a DoB curve, separately for the hydrogen or methanelevels, and for the isotopic ratio. Alternatively and preferably to theDoB, any of the other representations of the dose measured in theexhaled breaths, such as the PDR, may be used, as described hereinabove.These curves, or the data constituting them is then preferably input toa data analyzer, which detects the region of the peaks of the curves, asa function of elapsed time from administration of the test meals. In thecase of the hydrogen or methane data, it is not uncommon that nomeaningful peak can be detected, because a very broad and lowplateau-shaped curve is obtained. For this reason, the hydrogen ormethane analyzer unit is preferably pre-programmed that when nomeaningful peak can be extracted from the data, the algorithmalternatively detects the point in time when the hydrogen or methanelevel exceeds a predetermined level over the threshold, and this pointin time is used as a basis for defining the presence of a hydrogen ormethane “peak”. The differential time comparator then preferablycalculates the difference in time of occurrence of the two peaks,compares the resulting difference with a database of normal ranges ofthis time difference, and generates a test result for the breath test,based on the comparison of any measured time difference with theexpected norms.

Furthermore, according to further preferred embodiments of the presentinvention, there are provided kits for enabling the efficient and safeexecution of these described breath tests. The kit preferably comprisesthe required quantities of the two separate component substratematerials used in executing the particular test for which that kit issupplied. In order to ensure correct usage of the substrates and/ormarkers, a directions-for-use protocol (DFU) or a package insert ispreferably included in the kit. This protocol can preferably includesuch instructions as the preparation procedures for the meals, ifapplicable, and instructions for the addition of the marker materials ifapplicable. This protocol can also preferably include directions for theinterpretation of the results of the test, which could preferably be thecriteria for defining a set of time differential results as beingnormal, abnormal or borderline.

It will be appreciated by persons skilled in the art that the presentinvention is not limited by what has been particularly shown anddescribed hereinabove. Rather the scope of the present inventionincludes both combinations and subcombinations of various featuresdescribed hereinabove as well as variations and modifications theretowhich would occur to a person of skill in the art upon reading the abovedescription and which are not in the prior art.

We claim:
 1. A method for using a breath test for the determination ofgastro-intestinal disorders in a subject, the method comprising:detecting, using a first measurement of a breath test, the generation ofa predefined gas in said subject, after the subject was administered ameal comprising at least a first marker material and a second markermaterial, wherein said first marker material being such that it is notgenerally absorbed in the subject's stomach, and releases saidpredefined gas in the presence of intestinal bacteria, and wherein saidsecond marker material being such that it indicates a location of saidmeal within the subject's gastro-intestinal tract, determining, using asecond measurement of said breath test, the position within thesubject's gastro-intestinal tract at which said predefined gas isgenerated, using said second marker material, and evaluating saidgastro-intestinal condition of said subject from the outcome of saidbreath test.
 2. The method according to claim 1, wherein the methodfurther comprises: detecting a by-product of said second markermaterial, using said breath test, and determining the position of saidpredefined gas generation in the gastro-intestinal tract of saidsubject, by the temporal relationship between the appearance of saidpredefined gas and of said by-product of said marker material in saidsubject's breath.
 3. The method according to claim 2, wherein saidsecond marker material is labeled with a carbon isotope, and saidby-product is isotonically labeled carbon dioxide.
 4. The methodaccording to claim 2, wherein the method further comprises determiningwhether said subject is suffering from one or both of a sugarintolerance and a bacterial overgrowth, using a relative time andquantity of detection of said predefined gas and labeled by-products ofsaid second marker material, wherein said second material is anisotonically labeled material generally absorbed in the small intestine.5. The method according to claim 4, wherein the method further comprisesindicating that said subject is suffering a bacterial overgrowth, usingthe detection of a small quantity of said predetermined gas,characteristic of a small part of said first material in the presence ofbacteria, occurring concurrently with the detection of said labeledby-products of said second marker material.
 6. The method according toclaim 4, wherein the method further comprises indicating that saidsubject is suffering from said sugar intolerance, based on the detectionof said predefined gas later than the detection of said labeledby-products of said second marker material.
 7. The method according toclaim 4, wherein the method further comprises indicating that saidsubject is suffering said sugar intolerance and a bacterial overgrowth,based on the detection of a large quantity of said predefined gas,characteristic of the majority of said first material in the presence ofbacteria, occurring essentially concurrently with the detection of saidlabeled by-products of said second marker material.
 8. The methodaccording claim 1, wherein the method further comprises determining thepresence of bacterial overgrowth in the small intestine of said subject,using the time of detection of said predefined gas relative to the timeof detection of the second marker material, wherein said first materialis a sugar metabolized in said small intestine.
 9. The method accordingto claim 8, wherein the method further comprises indicating the presenceof bacterial overgrowth in said subject, based on the generallyconcurrent appearance in the breath of said subject of said predefinedgas and a by-product of said second marker material, wherein said secondmaterial is a labeled sugar also metabolized in the small intestine ofsaid subject.
 10. The method according to claim 8, wherein the methodfurther comprises indicating the absence of bacterial overgrowth in saidsubject, based on the appearance in the breath of said subject of aby-product of said second marker material significantly prior to theappearance of said predefined gas, wherein said second material is alabeled sugar also metabolized in the small intestine of said subject.11. The method according to claim 8, wherein said first material is atleast one of glucose and lactulose.
 12. The method according to claim 8,wherein said second material is at least one of labeled sodium acetate,sodium octanoate, glucose, an acetyl leucine probe, or amicroencapsulated labeled substrate.
 13. The method according to claim1, wherein the method further comprises determining the orocaecaltransit time of said subject, using detection of said predefined gasessentially concurrent with detection of a small quantity of said secondmarker material, wherein said first material is a sugar generallymetabolized in the small intestine of said subject.
 14. The methodaccording to claim 5, wherein the method further comprises determining asugar intolerance in said subject, using a time of detection of saidpredefined gas relative to a time of detection of the second markermaterial, wherein said first material is a sugar of a group malabsorbedby the small intestine of said subject, such that it arrives unabsorbedat the colon of said subject, where said predefined gas is generated bya presence of colonic bacteria.
 15. The method according to claim 14,wherein the method further comprises determining said sugar intolerancein said subject, using detection of said predefined gas concurrent withdetection of labeled by-products of said second marker material, whereinsaid second material is an isotonically labeled material generallyabsorbed in the colon.
 16. The method according to claim 15, whereinsaid second material is xylose labeled with a carbon isotope, and saidby-product is isotonically labeled carbon dioxide.
 17. The methodaccording to claim 14, wherein said sugar is at least one of the groupconsisting of lactose, fructose, maltose and sucrose.
 18. The methodaccording to claim 1, wherein said predefined gas is at least one ofhydrogen and methane.